View Filing Data

(Income) loss from discontinued operations, net of tax

$ 29,787

$ 26,910

5,484

2,158

Income (loss) from continuing operations

35,271

29,068

Adjustments to reconcile net income (loss) to net cash provided by operating activities:

Depreciation, depletion and amortization

38,559

31,910

Deferred financing cost amortization

2,719

1,528

Derivative fair value adjustments

1,594

2,010

Stock compensation

1,817

2,289

Unrealized mark-to-market (gain) loss on interest rate swaps

(12,045)

(5,465)

Deferred income taxes

18,083

25,844

Equity in (earnings) loss of unconsolidated subsidiaries

(993)

Allowance for funds used during construction - equity

(277)

(295)

Employee benefit plans

5,246

3,642

Other adjustments, net

2,187

(3,440)

Changes in certain operating assets and liabilities:

Materials, supplies and fuel

20,828

17,280

Accounts receivable and other current assets

9,439

(5,591)

Accounts payable and other current liabilities

(42,368)

(44,617)

Regulatory assets

(776)

33,966

Regulatory liabilities

18,938

9,984

Contributions to defined pension plans

(25,000)

Other operating activities, net

610

5,301

Net cash provided by operating activities of continuing operations

74,881

102,421

Net cash provided by (used in) operating activities of discontinued operations

21,184

8,850

Net cash provided by operating activities

96,065

111,271

Investing activities:

Property, plant and equipment additions

(67,652)

(121,615)

Other investing activities

1,105

786

Net cash provided by (used in) investing activities of continuing operations

(66,547)

(120,829)

Proceeds from sale of business operations

108,837

Net cash provided by (used in) investing activities of discontinued operations

(824)

(929)

Net cash provided by (used in) investing activities

41,466

(121,758)

Financing activities:

Dividends paid on common stock

(16,276)

(14,371)

Common stock issued

764

605

Short-term borrowings - issuances

56,453

210,000

Short-term borrowings - repayments

(176,453)

(172,000)

Long-term debt - repayments

(1,897)

(2,155)

Other financing activities

(2,758)

(14)

Net cash provided by (used in) financing activities of continuing operations

(140,167)

22,065

Net cash provided by (used in) financing activities of discontinued operations

Net cash provided by (used in) financing activities

(140,167)

22,065

Net change in cash and cash equivalents

(2,636)

11,578

Cash and cash equivalents:

Cash and cash equivalents, beginning of period

^[1]

58,768

32,438

Cash and cash equivalents, end of period

$ 56,132

44,016

^[1]

Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents

$ 17,600

[1]	Cash and cash equivalents include cash of discontinued operations of $37.1 million, $17.6 million and $16.0 million at December 31, 2011, March 31, 2011 and December 31, 2010, respectively.

Management's Statement	3 Months Ended
Management's Statement	Mar. 31, 2012
Management's Statement [Abstract]
Management's Statement	MANAGEMENT'S STATEMENT The unaudited Condensed Consolidated Financial Statements included herein have been prepared by Black Hills Corporation together with our subsidiaries (the "Company," "us," "we," or "our"), pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to such rules and regulations; however, we believe that the footnotes adequately disclose the information presented. These Condensed Consolidated Financial Statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2011 Annual Report on Form 10-K filed with the SEC. Accounting methods historically employed require certain estimates as of interim dates. The information furnished in the accompanying Condensed Consolidated Financial Statements reflects all adjustments, including accruals, which are, in the opinion of management, necessary for a fair presentation of the March 31, 2012, December 31, 2011 and March 31, 2011 financial information and are of a normal recurring nature. Certain industries in which we operate are highly seasonal and revenue from, and certain expenses for, such operations may fluctuate significantly among quarterly periods. Demand for electricity and natural gas is sensitive to seasonal cooling, heating and industrial load requirements, as well as changes in market price. In particular, the normal peak usage season for gas utilities is November through March and significant earnings variances can be expected between the Gas Utilities segment's peak and off-peak seasons. Due to this seasonal nature, our results of operations for the three months ended March 31, 2012 and March 31, 2011, and our financial condition as of March 31, 2012, December 31, 2011, and March 31, 2011 are not necessarily indicative of the results of operations and financial condition to be expected as of or for any other period. All earnings per share amounts discussed refer to diluted earnings per share unless otherwise noted. On February 29, 2012, we sold our Energy Marketing segment, which resulted in this segment being classified as discontinued operations. For comparative purposes, all prior periods presented have been restated to reflect the classification of this segment as discontinued operations. For further information see Note 17. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. Specifically, the Company has reclassified deferred financing cost amortization into a separate line on the Condensed Consolidated Statements of Cash Flow. This reclassification had no effect on total assets, net income, cash flows or earnings per share.

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 16: http://www.xbrl.org/2003/role/presentationRef
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Supplemental Cash Flow Information [Abstract]

Recently Adopted and Recently Issued Accounting Standards and Legislation	3 Months Ended
	Mar. 31, 2012
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Adopted and Recently Issued Accounting Standards and Legislation	RECENTLY ADOPTED AND RECENTLY ISSUED ACCOUNTING STANDARDS AND LEGISLATION Recently Adopted Accounting Standards and Legislation Other Comprehensive Income: Presentation of Comprehensive Income, ASU 2011-05 and ASU 2011-12 FASB issued an accounting standards update amending ASC 220, Comprehensive Income, to improve the comparability, consistency and transparency of reporting of comprehensive income. It amends existing guidance by allowing only two options for presenting the components of net income and other comprehensive income: (1) in a single continuous financial statement, statement of comprehensive income or (2) in two separate but consecutive financial statements, consisting of an income statement followed by a separate statement of other comprehensive income. Also, items that are reclassified from other comprehensive income to net income must be presented on the face of the financial statements. ASU 2011-05 requires retrospective application, and it is effective for the fiscal years, and interim periods within those years beginning after December 15, 2011. In December 2011, FASB issued ASU 2011-12 which indefinitely deferred the provisions of ASU 2011-05 requiring the presentation of reclassification adjustments on the face of the financial statements for items reclassified from other comprehensive income to net income. At December 31, 2011, we elected to early adopt the provisions of ASU 2011-05 as amended by ASU 2011-12. The adoption changed our presentation of certain financial statements and provided additional details in the notes to the financial statements, but did not have any other impact on our financial statements. Fair Value Measurement: Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements, ASU 2011-04 FASB issued an accounting standards update amending ASC 820, Fair Value Measurements and Disclosures, to achieve common fair value measurement and disclosure requirements between GAAP and IFRS. Additional disclosure requirements in the update include: (1) for Level 3 fair value measurements - quantitative information about unobservable inputs used, a description of the valuation processes used by the entity, and a qualitative discussion about the sensitivity of the measurements to changes in the unobservable inputs; (2) for an entity's use of a non-financial asset that is different from the asset's highest and best use - the reason for the difference; (3) for financial instruments not measured at fair value but for which disclosure of fair value is required - the fair value hierarchy level in which the fair value measurements were determined; and (4) the disclosure of all transfers between Level 1 and Level 2 of the fair value hierarchy. ASU 2011-04 is effective for fiscal years, and interim periods within those years, beginning after December 31, 2011. The amendment required additional details in notes to financial statements, but did not have any other impact on our financial statements. Additional disclosures are included in Notes 14 and 15. Intangibles - Goodwill and Other: Testing Goodwill for Impairment, ASU 2011-08 In September 2011, the FASB issued an amendment to ASC 350, Intangibles - Goodwill and Other, to provide an option to perform a qualitative assessment to determine whether further impairment testing of goodwill is necessary. Specifically, an entity has the option to first assess qualitative factors to determine whether it is necessary to perform the current two-step test. If an entity believes, as a result of its qualitative assessment, that it is more-likely-than-not that the fair value of a reporting unit is less than its carrying amount, the quantitative impairment test is required. Otherwise, no further testing is required. This standard is effective for annual and interim goodwill impairment testing performed for fiscal years beginning after December 15, 2011. We perform our annual impairment testing in November of each year. The adoption of this standard will not have an impact on our financial statements. Recently Issued Accounting Standards and Legislation Balance Sheet: Disclosure about Offsetting Assets and Liabilities, ASU 2011-11 In December 2011, the FASB issued revised accounting guidance to amend ASC 210, Balance Sheet, related to the existing disclosure requirements for offsetting financial assets and liabilities to enhance current disclosures, as well as to improve comparability of balance sheets prepared under GAAP and IFRS. The revised disclosure guidance affects all companies that have financial instruments and derivative instruments that are either offset in the balance sheet (i.e., presented on a net basis) or subject to an enforceable master netting and/or similar arrangement. In addition, the revised guidance requires that certain enhanced quantitative and qualitative disclosures are made with respect to a company's netting arrangements and/or rights of offset associated with its financial instruments and/or derivative instruments. The revised disclosure guidance is effective on a retrospective basis for interim and annual periods beginning January 1, 2013. Management does not believe that the adoption of this standard will have an impact on the Company’s financial position, results of operations or cash flows.

Supplemental Disclosure of Cash Flow Information

3 Months Ended

Mar. 31, 2012

Supplemental Disclosure of Cash Flow Information

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION



	Three Months Ended
	March 31, 2012			March 31, 2011
	(in thousands)
Non-cash investing activities from continuing operations—
Property, plant and equipment acquired with accrued liabilities	$	31,644		$	32,220
Capitalized assets associated with retirement obligations	$	2,826		$	—
Cash (paid) refunded during the period for continuing operations—
Interest (net of amounts capitalized)	$	(16,799	)	$	(11,572	)
Income taxes, net	$	(1,838	)	$	48

Materials, Supplies and Fuel

3 Months Ended

Mar. 31, 2012

Inventory, Net [Abstract]

Materials, Supplies and Fuel

MATERIALS, SUPPLIES AND FUEL

The amounts of Materials, supplies and fuel included in the accompanying Condensed Consolidated Balance Sheets, by major classification, were as follows (in thousands) as of:



	March 31, 2012		December 31, 2011		March 31, 2011
Materials and supplies	$	44,361	$	40,838	$	34,129
Fuel - Electric Utilities	7,812		8,201		9,307
Natural gas in storage - gas utilities	11,063		35,025		2,199
Total materials, supplies and fuel	$	63,236	$	84,064	$	45,635

Accounts Receivable

3 Months Ended

Mar. 31, 2012

Receivables [Abstract]

Accounts Receivable

ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS

Accounts receivable consists primarily of customer trade accounts. The Gas Utilities balance fluctuates primarily due to seasonality. We maintain an allowance for doubtful accounts that reflects our best estimate of probable uncollectible trade receivables. We regularly review our trade receivable allowances by considering such factors as historical experience, credit worthiness, the age of the receivable balances and current economic conditions that may affect our ability to collect.

Following is a summary of receivables (in thousands) as of:



	Accounts		Unbilled		Less Allowance for			Accounts
March 31, 2012	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	44,356	$	19,381	$	(585	)	$	63,152
Gas	44,287		18,502		(936		)	61,853
Oil and Gas	15,014		—		(105		)	14,909
Coal Mining	2,578		—		—			2,578
Power Generation	265		—		—			265
Corporate	1,230		—		—			1,230
Total	$	107,730	$	37,883	$	(1,626	)	$	143,987



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2011	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	42,773	$	21,151	$	(545	)	$	63,379
Gas	39,353		38,992		(1,011		)	77,334
Oil and Gas	11,282		—		(105		)	11,177
Coal Mining	4,056		—		—			4,056
Power Generation	282		—		—			282
Corporate	546		—		—			546
Total	$	98,292	$	60,143	$	(1,661	)	$	156,774



	Accounts		Unbilled		Less Allowance for			Accounts
March 31, 2011	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	46,077	$	16,196	$	(728	)	$	61,545
Gas	58,665		21,620		(1,763		)	78,522
Oil and Gas	7,503		—		(161		)	7,342
Coal Mining	982		—		—			982
Power Generation	2,050		—		—			2,050
Corporate	1,083		—		—			1,083
Total	$	116,360	$	37,816	$	(2,652	)	$	151,524

The entire disclosure for claims held for amounts due a company. Examples include trade accounts receivables, notes receivables, loans receivables.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 3, 4
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Position (SOP)
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Notes Payable

3 Months Ended

Mar. 31, 2012

Notes Payable [Abstract]

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

NOTES PAYABLE

Our credit facility and debt securities contain certain restrictive financial covenants. As of March 31, 2012, we were in compliance with all of these covenants.

We had the following short-term debt outstanding as of the Condensed Consolidated Balance Sheet dates (in thousands):



	March 31, 2012				December 31, 2011				March 31, 2011
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	75,000	$	41,200	$	195,000	$	43,700	$	187,000	$	51,000
Term Loan due 2011*	—		—		—		—		100,000		—
Term Loan due 2012	150,000		—		150,000		—		—		—
Total	$	225,000	$	41,200	$	345,000	$	43,700	$	287,000	$	51,000

______________

* The short-term loan was renegotiated to a longer term note, maturing in 2013.

Revolving Credit Facility

On February 1, 2012, we entered into a new $500 million Revolving Credit Facility expiring February 1, 2017 which contains an accordion feature allowing us, with the consent of the administrative agent, to increase the capacity of the facility to $750 million. The Revolving Credit Facility can be used for the issuance of letters of credit, to fund working capital needs and for other corporate purposes. Borrowings are available under a base rate option or a Eurodollar option. The cost of borrowings or letters of credit is determined based upon our credit ratings. At current credit ratings levels, the margins for base rate borrowings, Eurodollar borrowings and letters of credit were 0.50%, 1.50% and 1.50%, respectively, at March 31, 2012. The facility contains a commitment fee that is to be charged on the unused amount of the Revolving Credit Facility. Based upon current credit ratings, the fee is 0.25%.

Deferred financing costs on the new facility of $2.8 million are being amortized over the estimated useful life of the Revolving Credit Facility and are included in Interest expense on the accompanying Condensed Consolidated Statements of Income and Comprehensive Income. Upon entering into the new facility, $1.5 million of deferred financing costs relating to the previous credit facility were written off through Interest expense.

Debt Covenants

Certain debt obligations require compliance with the following covenants at the end of each quarter (dollars in thousands).



	As of			Covenant
	March 31, 2012			Requirement
Consolidated Net Worth	$	1,224,692		$	899,024
Recourse Leverage Ratio	56.4		%	65.0		%

Long-Term Debt	3 Months Ended
Long-Term Debt	Mar. 31, 2012
Long-term Debt, Unclassified [Abstract]
Long-term Debt [Text Block]	LONG TERM DEBT Pollution Control Revenue Bonds On March 28, 2012, Black Hills Power provided notice to the trustee of its intent to call the Pollution Control Refund Revenue Bonds which were originally due to mature on October 1, 2014. The principal amount due on the bonds has been reclassified to Current maturities of long-term debt on the accompanying Condensed Consolidated Balance Sheets. Repayment of $6.5 million principal and accrued interest will be made on May 15, 2012.

Earnings per Share

3 Months Ended

Mar. 31, 2012

Earnings Per Share [Abstract]

Earnings Per Share

EARNINGS PER SHARE

Basic earnings (loss) per share from continuing operations is computed by dividing Income (loss) from continuing operations by the weighted-average number of common shares outstanding during the period. Diluted earnings (loss) per share is computed by including all dilutive common shares potentially outstanding during a period. A reconciliation of share amounts used to compute earnings (loss) per share is as follows (in thousands):



	Three Months Ended March 31,
	2012		2011

Income (loss) from continuing operations	$	35,271	$	29,068

Weighted average shares - basic	43,731		39,059
Dilutive effect of:
Restricted stock	147		132
Stock options	18		17
Equity forward instruments	—		460
Other dilutive effects	73		93
Weighted average shares - diluted	43,969		39,761

The following outstanding securities were not included in the computation of diluted earnings per share as their effect would have been anti-dilutive (in thousands):



	Three Months Ended March 31,
	2012	2011
Stock options	127	83
Restricted stock	31	7
Other stock	16	—
Anti-dilutive shares	174	90

Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2012

Comprehensive Income (Loss)

COMPREHENSIVE INCOME (LOSS)

The following table presents the components of our comprehensive income (loss) (in thousands):



Three Months Ended March 31, 2012	Pre-tax Amount			Tax (Expense) Benefit		Net-of-tax Amount
Fair value adjustment of derivatives designated as cash flow hedges	$	521		$	55	$	576
Reclassification adjustments of cash flow hedges settled and included in net income (loss)	(1,187		)	445		(742		)
Other comprehensive income (loss)	$	(666	)	$	500	$	(166	)



Three Months Ended March 31, 2011	Pre-tax Amount			Tax (Expense) Benefit			Net-of-tax Amount
Fair value adjustment of derivatives designated as cash flow hedges	$	(3,785	)	$	1,637		$	(2,148	)
Reclassification adjustments of cash flow hedges settled and included in net income (loss)	861			(292		)	569
Other comprehensive income (loss)	$	(2,924	)	$	1,345		$	(1,579	)

Balances by classification included within Accumulated other comprehensive income (loss) on the accompanying Condensed Consolidated Balance Sheets are as follows (in thousands):



	Derivatives Designated as Cash Flow Hedges			Employee Benefit Plans			Total
Balance as of December 31, 2011	$	(13,802	)	$	(19,076	)	$	(32,878	)
Other comprehensive income (loss)	(166		)	—			(166		)
Ending Balance March 31, 2012	$	(13,968	)	$	(19,076	)	$	(33,044	)

	Derivatives Designated as Cash Flow Hedges			Employee Benefit Plans			Total
Balance as of December 31, 2010	$	(12,439	)	$	(11,142	)	$	(23,581	)
Other comprehensive income (loss)	(1,579		)	—			(1,579		)
Ending Balance March 31, 2011	$	(14,018	)	$	(11,142	)	$	(25,160	)

The entire disclosure for comprehensive income. Includes, but is not limited to, the following: 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income. Components of comprehensive income include: (1) foreign currency translation adjustments; (2) gains (losses) on foreign currency transactions that are designated as, and are effective as, economic hedges of a net investment in a foreign entity; (3) gains (losses) on intercompany foreign currency transactions that are of a long-term-investment nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements; (4) change in the market value of a futures contract that qualifies as a hedge of an asset reported at fair value; (5) unrealized holding gains (losses) on available-for-sale securities and that resulting from transfers of debt securities from the held-to-maturity category to the available-for-sale category; (6) a net loss recognized as an additional pension liability not yet recognized as net periodic pension cost; and (7) the net gain (loss) and net prior service cost or credit for pension plans and other postretirement benefit plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 14-26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e637-108580

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-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e681-108580

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-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e653-108580

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

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-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e709-108580

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-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6920433&loc=d3e998-108581

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-Name Accounting Standards Codification
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-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e640-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e716-108580

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-Name Accounting Standards Codification
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-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e689-108580

Common Stock, Including Additional Paid in Capital, Net of Discount [Abstract]

Common Stock

3 Months Ended

Mar. 31, 2012

Common Stock

COMMON STOCK

Other than the following transactions, we had no material changes in our common stock during the three months ended March 31, 2012 from the amount reported in Note 11 of the Notes to Consolidated Financial Statements in our 2011 Annual Report on Form 10-K.

Equity Compensation Plans

•

We granted 66,690 target performance shares to certain officers and business unit leaders for the January 1, 2012 through December 31, 2014 performance period during the three months ended March 31, 2012. Actual shares are issued after the end of the performance plan period. Performance shares are awarded based on our total stockholder return over the designated performance period as measured against a selected peer group and can range from 0% to 200% of target. In addition, certain stock price performance must be achieved for a payout to occur. The final value of the performance shares will vary according to the number of shares of common stock that are ultimately granted based upon the actual level of attainment of the performance criteria. The performance awards are paid 50% in the form of cash and 50% in shares of common stock. The grant date fair value was $32.26 per share.


•	We granted 139,550 shares of restricted common stock and restricted stock units during the three months ended March 31, 2012. The pre-tax compensation cost related to the awards of restricted stock and restricted stock units of approximately $4.9 million will be recognized over the vesting period.


•	Stock options totaling 41,206 shares were exercised during the three months ended March 31, 2012 at a weighted-average exercise price of $28.28 per share, providing $1.2 million of proceeds.


•	We issued 3,690 shares of common stock under our short-term incentive compensation plan during the three months ended March 31, 2012. Pre-tax compensation cost related to the awards was approximately $0.1 million, which was expensed in 2011.

Stock-based compensation expense for the three months ended March 31, 2012 and 2011 was $1.8 million and $2.3 million, respectively.

As of March 31, 2012, total unrecognized compensation expense related to non-vested stock awards was $12.2 million and is expected to be recognized over a weighted-average period of 2.3 years.

Dividend Reinvestment and Stock Purchase Plan

We have a DRIP under which stockholders may purchase additional shares of common stock through dividend reinvestment and/or optional cash payments at 100% of the recent average market price. We have the option of issuing new shares or purchasing the shares on the open market. We are issuing new shares. We issued 27,155 new shares at a weighted-average price of $33.20 during the three months ended March 31, 2012. Unissued common stock totaling 426,109 shares was available for future offering under the DRIP at March 31, 2012.

Dividend Restrictions

Our Revolving Credit Facility and other debt obligations contain restrictions on the payment of cash dividends upon a default or event of default. As of March 31, 2012, we were in compliance with these covenants.

Due to our holding company structure, substantially all of our operating cash flows are provided by dividends paid or distributions made by our subsidiaries. The cash to pay dividends to our stockholders is derived from these cash flows. As a result, certain statutory limitations or regulatory or financing agreements could affect the levels of distributions allowed to be made by our subsidiaries. The following restrictions on distributions from our subsidiaries existed at March 31, 2012:


•	Our utilities are generally limited to the amount of dividends allowed to be paid to us as a utility holding company under the Federal Power Act and settlement agreements with state regulatory jurisdictions. As of March 31, 2012, the restricted net assets at our Utilities Group were approximately $81.4 million.


•	As required by the covenant in the Black Hills Wyoming project financing, Black Hills Non-regulated Holdings has maintained restricted equity of at least $100.0 million.

The entire disclosure for shareholders' equity, comprised of portions attributable to the parent entity and noncontrolling interest, if any, including other comprehensive income (as applicable). Including, but not limited to: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms, and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables, effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph d

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7, 11A
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Name Statement of Financial Accounting Standard (FAS)
-Number 129
-Paragraph 2, 3, 4, 5, 6, 7, 8
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-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

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-Number 5
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-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

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-Number Topic 4
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-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
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-Name Accounting Standards Codification
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 20: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=6228006&loc=d3e74512-122707

Reference 21: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 22: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 23: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187143-122770

Employee Benefit Plans

3 Months Ended

Mar. 31, 2012

Employee Benefit Plans [Abstract]

Employee Benefit Plans

EMPLOYEE BENEFIT PLANS

Defined Benefit Pension Plans

We have three non-contributory defined benefit pension plans (the "Pension Plans"). One covers certain eligible employees of the following subsidiaries: Black Hills Service Company, Black Hills Power, WRDC and BHEP, one covers certain eligible employees of Cheyenne Light, and one covers certain eligible employees of Black Hills Energy. The Pension Plan benefits are based on years of service and compensation levels.

The components of net periodic benefit cost for the Pension Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012			2011
Service cost	$	1,430		$	1,355
Interest cost	3,687			3,732
Expected return on plan assets	(4,084		)	(4,239		)
Prior service cost	22			25
Net loss (gain)	2,408			1,135
Net periodic benefit cost	$	3,463		$	2,008

Non-pension Defined Benefit Postretirement Healthcare Plans

We sponsor the following retiree healthcare plans (the "Healthcare Plans"): the Black Hills Corporation Postretirement Healthcare Plan, the Healthcare Plan for Retirees of Cheyenne Light, and the Black Hills Energy Postretirement Healthcare Plan. Employees who participate in the Healthcare Plans and who retire on or after meeting certain eligibility requirements are entitled to postretirement healthcare benefits.

The components of net periodic benefit cost for the Healthcare Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012			2011
Service cost	$	402		$	375
Interest cost	523			542
Expected return on plan assets	(19		)	(41		)
Prior service cost (benefit)	(125		)	(120		)
Net loss (gain)	222			169
Net periodic benefit cost	$	1,003		$	925

Supplemental Non-qualified Defined Benefit Plans

We have various supplemental retirement plans for key executives (the "Supplemental Plans"). The Supplemental Plans are non-qualified defined benefit plans.

The components of net periodic benefit cost for the Supplemental Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012		2011
Service cost	$	246	$	257
Interest cost	331		324
Prior service cost	1		1
Net loss (gain)	202		127
Net periodic benefit cost	$	780	$	709

Contributions

We anticipate that we will make contributions to the benefit plans during 2012 and 2013. Contributions to the Defined Benefit Plans will be made in cash and contributions to the Healthcare Plans and the Supplemental Plans are expected to be made in the form of benefit payments. Contributions are as follows (in thousands):



	Contributions Made
	Three Months Ended March 31, 2012		Additional Contributions Anticipated for 2012		Contributions Anticipated for 2013
Defined Benefit Pension Plans	$	25,000	$	—	$	4,500
Non-pension Defined Benefit Postretirement Healthcare Plans	$	1,063	$	3,188	$	4,380
Supplemental Non-qualified Defined Benefit Plans	$	278	$	833	$	1,090

The entire disclosure for pension and other postretirement benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
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-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
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-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
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-Subparagraph m
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
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-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-2
-Paragraph 8
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-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 30
-Paragraph 26
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 7, 21, 22
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5, 6, 7, 8
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-Publisher FASB
-Name Implementation Guide (Q and A)
-Number FAS88
-Paragraph 63
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-URI http://asc.fasb.org/topic&trid=2235017

Segment Reporting Information, Additional Information [Abstract]

Segment Reporting

3 Months Ended

Mar. 31, 2012

Summary of Information Relating to Segments of our Business

BUSINESS SEGMENTS INFORMATION

Our reportable segments are based on our method of internal reporting, which generally segregates the strategic business groups due to differences in products, services and regulation. All of our operations and assets are located within the United States.

On February 29, 2012, we sold our Energy Marketing segment, Enserco, which resulted in this segment being classified as discontinued operations. For comparative purposes, all prior periods presented have been restated to reflect the classification of this segment as discontinued operations. Indirect corporate costs and inter-segment interest expense related to Enserco that have not been classified as discontinued operations reclassified to our Corporate segment. For further information see Note 17.

We conduct our operations through the following five reportable segments:

Utilities Group —


•	Electric Utilities, which supplies electric utility service to areas in South Dakota, Wyoming, Colorado and Montana and natural gas utility service to Cheyenne, Wyoming and vicinity; and


•	Gas Utilities, which supplies natural gas utility service to areas in Colorado, Iowa, Kansas and Nebraska.

Non-regulated Energy Group —


•	Oil and Gas, which acquires, explores for, develops and produces crude oil and natural gas interests located in the Rocky Mountain region and other states;


•	Power Generation, which produces and sells power and capacity to wholesale customers from power plants located in Wyoming and Colorado; and


•	Coal Mining, which engages in the mining and sale of coal from our mine near Gillette, Wyoming.

Segment information follows the accounting policies described in Note 1 of the Notes to Consolidated Financial Statements in our 2011 Annual Report on Form 10-K.

Segment information included in the accompanying Condensed Consolidated Statements of Income and Comprehensive Income and Condensed Consolidated Balance Sheets was as follows (in thousands):



Three Months Ended March 31, 2012	External Operating Revenues		Intercompany Operating Revenues			Income (Loss) from Continuing Operations
Utilities:
Electric	$	156,133	$	3,036		$	8,746
Gas	180,522		—			15,207
Non-regulated Energy:
Oil and Gas	21,645		—			13
Power Generation	1,178		18,449			6,914
Coal Mining	6,373		8,616			1,000
Corporate ^(a)(b)	—		—			3,391
Intercompany eliminations	—		(30,101		)	—
Total	$	365,851	$	—		$	35,271



Three Months Ended March 31, 2011	External Operating Revenues		Intercompany Operating Revenues			Income (Loss) from Continuing Operations
Utilities:
Electric	$	144,430	$	3,839		$	10,249
Gas	230,266		—			19,263
Non-regulated Energy:
Oil and Gas	17,906		—			(715		)
Power Generation	687		6,933			1,186
Coal Mining	7,614		7,881			(1,298		)
Corporate ^(a)(b)	—		—			451
Intercompany eliminations	—		(18,721		)	(68		)
Total	$	400,903	$	(68	)	$	29,068

____________


(a)	Income (loss) from continuing operations includes $7.8 million and $3.6 million net after-tax mark-to-market gain on interest rate swaps for the three months ended March 31, 2012 and March 31, 2011, respectively.


(b)	Certain direct corporate costs and inter-segment interest expense previously allocated to our Energy Marketing segment were not classified as discontinued operations but were included in the Corporate segment. See Note 17 for further information.



Total Assets (net of inter-company eliminations)	March 31, 2012		December 31, 2011		March 31, 2011
Utilities:
Electric^(a)	$	2,268,524	$	2,254,914	$	1,868,600
Gas	717,185		746,444		683,927
Non-regulated Energy:
Oil and Gas	430,851		425,970		355,357
Power Generation^(a)	128,225		129,121		336,827
Coal Mining	87,139		88,704		94,416
Corporate ^(b)	176,012		141,079		94,499
Discontinued operations ^(c)	—		340,851		295,724
Total assets	$	3,807,936	$	4,127,083	$	3,729,350

____________


(a)	The PPA under which the new generating facility was constructed at our Pueblo Airport Generation site by Colorado IPP to support Colorado Electric customers is accounted for as a capital lease. Therefore, commencing December 31, 2011, assets previously at Power Generation are now accounted for at Colorado Electric under accounting for a capital lease.

(b) Assets of the Corporate segment were restated due to deferred taxes that were not classified as discontinued operations.

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Risk Management Activities [Abstract]

Risk Management Activities

3 Months Ended

Mar. 31, 2012

Risk Management Activities

RISK MANAGEMENT ACTIVITIES

Our activities in the regulated and non-regulated energy sectors expose us to a number of risks in the normal operation of our businesses. Depending on the activity, we are exposed to varying degrees of market risk and credit risk. To manage and mitigate these identified risks, we have adopted the Black Hills Corporation Risk Policies and Procedures as discussed in our 2011 Annual Report on Form 10-K filed with the SEC.

Market Risk

Market risk is the potential loss that might occur as a result of an adverse change in market price or rate. We are exposed to the following market risks:


•	Commodity price risk associated with our natural long position with crude oil and natural gas reserves and production, fuel procurement for certain of our gas-fired generation assets and variability in revenue due to changes in gas usage at our regulated segment; and


•	Interest rate risk associated with our variable rate credit facility, project financing floating rate debt and our derivative instruments.

Our exposure to these market risks is affected by a number of factors including the size, duration, and composition of our energy portfolio, the absolute and relative levels of interest rates and commodity prices, the volatility of these prices and rates, and the liquidity of the related interest rate and commodity markets.

Credit Risk

Credit risk is the risk of financial loss resulting from non-performance of contractual obligations by a counterparty.

For production and generation activities, we attempt to mitigate our credit exposure by conducting business primarily with investment grade companies and credit quality municipalities and electric cooperatives, setting tenor and credit limits commensurate with counterparty financial strength, obtaining master netting agreements, and mitigating credit exposure with less creditworthy counterparties through parental guarantees, prepayments, letters of credit, and other security agreements.

We perform ongoing credit evaluations of our customers and adjust credit limits based upon payment history and the customer's current creditworthiness, as determined by review of their current credit information. We maintain a provision for estimated credit losses based upon historical experience and any specific customer collection issue that is identified.

As of March 31, 2012, our credit exposure (exclusive of retail customers of the regulated utilities) was concentrated primarily among investment grade companies. Credit exposure with non-investment grade or non-rated counterparties, was supported partially through letters of credit, prepayments or parental guarantees.

We actively manage our exposure to certain market and credit risks as described in Note 3 of the Notes to the Consolidated Financial Statements in our 2011 Annual Report on Form 10-K. Our derivative and hedging activities included in the accompanying Condensed Consolidated Balance Sheets and Condensed Consolidated Statements of Income and Comprehensive Income are detailed below and within Note 14.

Oil and Gas Exploration and Production

We produce natural gas and crude oil through our exploration and production activities. Our natural "long" positions, or unhedged open positions, result in commodity price risk and variability to our cash flows.

We hold a portfolio of swaps and options to hedge portions of our crude oil and natural gas production. We elect hedge accounting on those OTC swaps and options. These transactions were designated at inception as cash flow hedges, documented under accounting for derivatives and hedging, and initially met prospective effectiveness testing. Effectiveness of our hedging position is evaluated at least quarterly.

The derivatives were marked to fair value and are recorded as Derivative assets or Derivative liabilities on the accompanying Condensed Consolidated Balance Sheets. The effective portion of the gain or loss on these derivatives is reported in Accumulated other comprehensive income (loss) and the ineffective portion, if any, is reported in Revenue.

We had the following derivatives and related balances (dollars in thousands) as of:



	March 31, 2012					December 31, 2011					March 31, 2011
	Crude Oil Swaps/ Options			Natural Gas Swaps		Crude Oil Swaps/ Options			Natural Gas Swaps		Crude Oil Swaps/ Options			Natural Gas Swaps
Notional ^(a)	522,000			5,001,750		528,000			5,406,250		487,500			5,974,800
Maximum terms in years ^(b)	1.25			1.50		1.25			1.75		1.00			0.25
Derivative assets, current	$	406		$	8,256	$	729		$	8,010	$	108		$	6,649
Derivative assets, non-current	$	46		$	808	$	771		$	1,148	$	—		$	975
Derivative liabilities, current	$	2,904		$	—	$	2,559		$	—	$	4,688		$	—
Derivative liabilities, non-current	$	1,084		$	—	$	811		$	7	$	2,678		$	157
Pre-tax accumulated other comprehensive income (loss)	$	(3,566	)	$	9,064	$	(1,928	)	$	9,152	$	(7,613	)	$	7,467
Revenue ^(c)	$	30		$	—	$	58		$	—	$	355		$	—

____________


(a)	Crude oil in Bbls, gas in MMBtus


(b)	Refers to the term of the derivative instrument. Assets and liabilities are classified as current or non-current based on the term of the hedged transaction and the corresponding settlement of the derivative instruments.


(c)	Represents the amortization of put premiums.

Based on March 31, 2012 market prices, a $4.3 million gain would be reclassified from AOCI during the next 12 months. Estimated and actual realized gains will change during future periods as market prices fluctuate.

Utilities

Our utility customers are exposed to the effect of volatile natural gas prices; therefore, as allowed or required by state utility commissions, we have entered into certain exchange-traded natural gas futures, options and basis swaps to reduce our customers' underlying exposure to these fluctuations. These transactions are considered derivatives and in accordance with accounting standards for derivatives and hedging, mark-to-market adjustments are recorded as Derivative assets or Derivative liabilities on the accompanying Condensed Consolidated Balance Sheets. Gains and losses, as well as option premiums and commissions, on these transactions are recorded as Regulatory assets or Regulatory liabilities in accordance with accounting standards for regulated operations. Accordingly, the earnings impact is recognized in the Condensed Consolidated Statements of Income and Comprehensive Income when the related costs are recovered through our rates.

The contract or notional amounts and terms of the natural gas derivative commodity instruments held at our Utilities were as follows as of:



	March 31, 2012		December 31, 2011		March 31, 2011
	Notional (MMBtus)	Latest Expiration (months)	Notional (MMBtus)	Latest Expiration (months)	Notional (MMBtus)	Latest Expiration (months)
Natural gas futures purchased	11,550,000	81	14,310,000	84	4,680,000	24
Natural gas options purchased	670,000	12	1,720,000	3	—	—
Natural gas basis swaps purchased	7,640,000	81	7,160,000	60	—	—

We had the following derivative balances related to the hedges in our Utilities (in thousands) as of:



	March 31, 2012		December 31, 2011		March 31, 2011
Derivative assets, current	$	9,215	$	9,844	$	1,056
Derivative assets, non-current	$	27	$	52	$	209
Derivative liabilities, non-current	$	6,407	$	7,156	$	—
Net unrealized gain (loss) included in Regulatory assets or liabilities	$	15,223	$	17,556	$	2,455
Included in Derivatives:
Cash collateral receivable (payable)	$	17,651	$	19,416	$	3,720
Option premiums and commissions	$	407	$	880	$	—

Financing Activities

We have entered into floating-to-fixed interest rate swap agreements to reduce our exposure to interest rate fluctuations associated with our floating rate debt obligations. Our interest rate swaps and related balances were as follows (dollars in thousands) as of:



	March 31, 2012						December 31, 2011						March 31, 2011
	Designated Interest Rate Swaps			De-designated Interest Rate Swaps*			Designated Interest Rate Swaps			De-designated Interest Rate Swaps*			Designated Interest Rate Swaps			De-designated Interest Rate Swaps*
Notional	$	150,000		$	250,000		$	150,000		$	250,000		$	150,000		$	250,000
Weighted average fixed interest rate	5.04		%	5.67		%	5.04		%	5.67		%	5.04		%	5.67		%
Maximum terms in years	4.75			1.75			5.00			2.00			5.75			0.75
Derivative liabilities, current	$	6,777		$	66,708		$	6,513		$	75,295		$	6,769		$	48,515
Derivative liabilities, non-current	$	18,441		$	17,237		$	20,363		$	20,696		$	12,955		$	—
Pre-tax accumulated other comprehensive income (loss)	$	(25,218	)	$	—		$	(26,876	)	$	—		$	(19,724	)	$	—
Pre-tax gain (loss)	$	—		$	12,045		$	—		$	(42,010	)	$	—		$	5,465
Cash collateral receivable (payable)	$	—		$	—		$	—		$	—		$	—		$	—

_____________


*	Maximum terms in years reflect the amended early termination dates. If the early termination dates are not extended, the swaps will require cash settlement based on the swap value on the termination date. If extended, de-designated swaps totaling $100 million terminate in 7 years and de-designated swaps totaling $150 million terminate in 17 years.

$50 million of our de-designated swaps have collateral requirements based on our corporate credit ratings. At our current credit ratings, we would be required to post collateral for any amount by which the swaps' negative mark-to-market fair value exceeds $20 million. If our senior unsecured credit rating drops to BB+ or below by S&P, or Ba1 or below by Moody's, we would be required to post collateral for the entire amount of the swaps' negative mark-to-market fair value.

Based on March 31, 2012 market interest rates and balances related to our designated interest rate swaps, a loss of approximately $6.8 million would be reclassified from AOCI during the next 12 months. Estimated and realized losses will change during future periods as market interest rates change

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]

Fair Value Measurements

3 Months Ended

Mar. 31, 2012

Fair Value Measurements [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Derivative Financial Instruments

Assets and liabilities carried at fair value are classified and disclosed in one of the following categories:

Level 1 — Unadjusted quoted prices available in active markets that are accessible at the measurement date for identical unrestricted assets or liabilities. This level primarily consists of financial instruments such as exchange-traded securities or listed derivatives.

Level 2 — Pricing inputs include quoted prices for identical or similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means.

Level 3 — Pricing inputs include significant inputs that are generally less observable from objective sources. These inputs reflect management's best estimate of fair value using its own assumptions about the assumptions a market participant would use in pricing the asset or liability.

Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the placement within the fair value hierarchy levels. We record transfers, if necessary, between levels at the end of the reporting period for all of our financial instruments.

Valuation Methodologies

Oil and Gas Segment:


•	The commodity option contracts for the Oil and Gas segment are valued under the market approach and include calls and puts. Fair value was derived using quoted prices from third party brokers for similar instruments as to quantity and timing. The prices are then validated through multiple sources.


•	The commodity basis swaps for the Oil and Gas segment are valued under the market approach using the instrument's current forward price strip hedged for the same quantity and date and discounted based on the three-month LIBOR.

Utilities Segment:

•

The commodity contracts for the Utilities, valued using the market approach, include exchange-traded futures, options and basis swaps (Level 2) and OTC basis swaps (Level 3) for natural gas contracts. For Level 2 assets and liabilities, fair value was derived using broker quotes validated by the Chicago Mercantile Exchange pricing for similar instruments. For Level 3 assets and liabilities, fair value was derived using average price quotes from the OTC contract broker and an independent third party market participant.

Corporate Segment:

•

The interest rate swaps are valued using the market valuation approach. The company establishes fair value by obtaining price quotes directly from the counterparty which are based on the floating three-month LIBOR curve for the term of the contract. The fair value obtained from the counterparty is then validated by utilizing a nationally recognized service that obtains observable inputs to compute fair value for the same instrument. In addition, the fair value for the interest rate swap derivatives includes a CVA component. The CVA considers the fair value of the interest rate swap and the probability of default based on the life of the contract. For the probability of a default component, we utilize observable inputs supporting Level 2 disclosure by using our credit default spread, if available, or a generic credit default spread curve that takes into account our credit ratings.

Recurring Fair Value Measurements

The following tables set forth by level within the fair value hierarchy our assets and liabilities that were accounted for at fair value on a recurring basis (in thousands):



	As of March 31, 2012
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	404		$	—	$	—	$	—	$	404
Basis Swaps -- Oil	—		48			—		—		—		48
Options -- Gas	—		—			—		—		—		—
Basis Swaps -- Gas	—		9,064			—		—		—		9,064
Commodity derivatives — Utilities	—		(8,412		)	3		—		17,651		9,242
Repurchase agreement ^(a)	43,128		—			—		—		—		43,128
Money market funds and term deposits ^(a)	12,791		—			—		—		—		12,791
Total	$	55,919	$	1,104		$	3	$	—	$	17,651	$	74,677

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	1,347		$	—	$	—	$	—	$	1,347
Basis Swaps -- Oil	—		2,641			—		—		—		2,641
Options -- Gas	—		—			—		—		—		—
Basis Swaps -- Gas	—		—			—		—		—		—
Commodity derivatives — Utilities	—		6,359			48		—		—		6,407
Interest rate swaps	—		109,163			—		—		—		109,163
Total	$	—	$	119,510		$	48	$	—	$	—	$	119,558

______________

(a) Level 1 assets and liabilities and described at Note 15.



	As of December 31, 2011
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas	$	—	$	9,885		$	768	$	5	$	—	$	10,658
Commodity derivatives —Utilities	—		(9,520		)	—		—		19,416		9,896
Money market funds	6,005		—			—		—		—		6,005
Total	$	6,005	$	365		$	768	$	5	$	19,416	$	26,559

Liabilities:
Commodity derivatives — Oil and Gas	$	—	$	2,207		$	1,165	$	5	$	—	$	3,377
Commodity derivatives — Utilities	—		7,156			—		—		—		7,156
Interest rate swaps	—		122,867			—		—		—		122,867
Total	$	—	$	132,230		$	1,165	$	5	$	—	$	133,400



	As of March 31, 2011
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas	$	—	$	7,626		$	106	$	—	$	—	$	7,732
Commodity derivatives — Utilities	—		(2,455		)	—		—		3,720		1,265
Money market funds	9,050		—			—		—		—		9,050
Total	$	9,050	$	5,171		$	106	$	—	$	3,720	$	18,047

Liabilities:
Commodity derivatives — Oil and Gas	$	—	$	7,523		$	—	$	—	$	—	$	7,523
Commodity derivatives — Utilities	—		—			—		—		—		—
Interest rate swaps	—		68,239			—		—		—		68,239
Total	$	—	$	75,762		$	—	$	—	$	—	$	75,762

The following table presents the quantitative information about level 3 fair value measurements (dollars shown in thousands):



	Fair Value at		Valuation	Unobservable	Range (Weighted
	March 31, 2012		Technique	Input	Average)
ASSETS
Commodity derivatives - Utilities^(a)	$	3	Independent price quotes	Long-term natural gas prices	Not applicable

LIABILITIES
Commodity derivatives - Utilities^(a)	$	48	Independent price quotes	Long-term natural gas prices	Not applicable

______________________

(a)

The significant unobservable inputs used in the fair value measurement of the long-term OTC contracts are based on the average of price quotes from an independent third party market participant and the OTC contract broker. Significant changes to these inputs along with the contract term would impact the derivative asset/liability and regulatory asset/liability, but will not impact the results of operations until the contract is settled under the original terms of the contract. The contracts will be classified as Level 2 once settlement is within 60 months of maturity and quoted market prices from a market exchange are available.

The following tables present the changes in Level 3 recurring fair value for the three months ended March 31, 2012 and 2011, respectively (in thousands):



	Three Months Ended March 31, 2012
Assets:	Commodity Derivatives -- Oil			Commodity Derivatives -- Gas		Commodity Derivatives -- Utilities		Total
Balances as of beginning of period	$	768		$	—	$	—	$	768
Total gain (loss) included in revenue	—			—		—		—
Total gain (loss) included in AOCI	(360		)	—		—		(360		)
Purchases	—			—		3		3
Issuances	—			—		—		—
Settlements	(4		)	—		—		(4		)
Transfers into level 3^(a)	—			—		—		—
Transfers out of level 3^(b)(c)	(404		)	—		—		(404		)
Balances at end of period	$	—		$	—	$	3	$	3

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	—		$	—	$	3	$	3



	Three Months Ended March 31, 2012
Liabilities:	Commodity Derivatives -- Oil			Commodity Derivatives -- Gas		Commodity Derivatives -- Utilities		Total
Balances as of beginning of period	$	1,165		$	—	$	—	$	1,165
Total gain (loss) included in revenue	—			—		—		—
Total gain (loss) included in AOCI	182			—		—		182
Purchases	—			—		48		48
Issuances	—			—		—		—
Settlements	—			—		—		—
Transfers into level 3^(a)	—			—		—		—
Transfers out of level 3^(b)(c)	(1,347		)	—		—		(1,347		)
Balances at end of period	$	—		$	—	$	48	$	48

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	—		$	—	$	48	$	48



	Three Months Ended March 31, 2011
	Commodity Derivatives
Balance as of beginning of period	$	266
Unrealized losses	(160		)
Unrealized gains	—
Settlements	—
Transfers into level 3^(a)	—
Transfers out of level 3^(b)	—
Balance at end of period	$	106

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	(159	)

____________


(a)	Transfers into Level 3 would occur when significant inputs used to value the derivative instruments become less observable such as a significant decrease in the frequency and volume in which the instrument is traded, negatively impacting the availability of observable pricing inputs.


(b)	Transfers out of Level 3 would occur when the significant inputs become more observable such as the time between the valuation date and the delivery date of a transaction becomes shorter, positively impacting the availability of observable pricing inputs.

(c) Previously, we utilized pricing methodologies developed by our Energy Marketing segment to value our Oil and Gas derivatives. Oil and Gas now obtains available observable inputs including quoted prices traded on active exchanges from multiple sources to value our options. Therefore, options in the Oil and Gas segment have been reclassified from Level 3 to Level 2.

Fair Value Measures

As required by accounting standards for derivatives and hedges, fair values within the following tables are presented on a gross basis and do not reflect the netting of asset and liability positions permitted in accordance with accounting standards for offsetting and under terms of our master netting agreements. Further, the amounts do not include net cash collateral on deposit in margin accounts at March 31, 2012, December 31, 2011, and March 31, 2011, to collateralize certain financial instruments, which are included in Derivative assets and/or Derivative liabilities. Therefore, the gross balances are not indicative of either our actual credit exposure or net economic exposure. Additionally, the amounts below will not agree with the amounts presented on our Condensed Consolidated Balance Sheets, nor will they correspond to the fair value measurements presented in Note 13.

The following tables present the fair value and balance sheet classification of our derivative instruments (in thousands):



As of March 31, 2012
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	8,662	$	—
Commodity derivatives	Derivative assets — non-current	854		—
Commodity derivatives	Derivative liabilities — current	—		2,904
Commodity derivatives	Derivative liabilities — non-current	—		1,084
Interest rate swaps	Derivative liabilities — current	—		6,777
Interest rate swaps	Derivative liabilities — non-current	—		18,441
Total derivatives designated as hedges		$	9,516	$	29,206

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	8,436
Commodity derivatives	Derivative assets — non-current	—		(27		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		6,407
Interest rate swaps	Derivative liabilities — current	—		66,708
Interest rate swaps	Derivative liabilities — non-current	—		17,237
Total derivatives not designated as hedges		$	—	$	98,761



As of December 31, 2011
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	8,739	$	—
Commodity derivatives	Derivative assets — non-current	1,919		—
Commodity derivatives	Derivative liabilities — current	—		2,559
Commodity derivatives	Derivative liabilities — non-current	—		818
Interest rate swaps	Derivative liabilities — current	—		6,513
Interest rate swaps	Derivative liabilities — non-current	—		20,363
Total derivatives designated as hedges		$	10,658	$	30,253

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	9,572
Commodity derivatives	Derivative assets — non-current	—		(52		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		7,156
Interest rate swaps	Derivative liabilities — current	—		75,295
Interest rate swaps	Derivative liabilities — non-current	—		20,696
Total derivatives not designated as hedges		$	—	$	112,667



As of March 31, 2011
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	6,757	$	—
Commodity derivatives	Derivative assets — non-current	975		—
Commodity derivatives	Derivative liabilities — current	—		4,688
Commodity derivatives	Derivative liabilities — non-current	—		2,835
Interest rate swaps	Derivative liabilities — current	—		6,769
Interest rate swaps	Derivative liabilities — non-current	—		12,955
Total derivatives designated as hedges		$	7,732	$	27,247

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	2,665
Commodity derivatives	Derivative assets — non-current	—		(209		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		—
Interest rate swaps	Derivative liabilities — current	—		48,515
Interest rate swaps	Derivative liabilities — non-current	—		—
Total derivatives not designated as hedges		$	—	$	50,971

A description of our derivative activities is included in Note 13. The following tables present the impact that derivatives had on our Condensed Consolidated Statements of Income and Comprehensive Income.

Cash Flow Hedges

The impact of cash flow hedges on our Condensed Consolidated Statements of Income and Comprehensive Income was as follows (in thousands):



Three Months Ended March 31, 2012
Derivatives in Cash Flow Hedging Relationships	Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)			Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)	Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)
Interest rate swaps	$	(762	)	Interest expense	$	(1,822	)		$	—
Commodity derivatives	1,283			Revenue	3,009				—
Total	$	521			$	1,187			$	—



Three Months Ended March 31, 2011
Derivatives in Cash Flow Hedging Relationships	Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)			Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)	Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)
Interest rate swaps	$	298		Interest expense	$	(1,892	)		$	—
Commodity derivatives	(4,083		)	Revenue	1,031				—
Total	$	(3,785	)		$	(861	)		$	—

Derivatives Not Designated as Hedge Instruments

The impact of derivative instruments that have not been designated as hedging instruments on our Condensed Consolidated Statements of Income and Comprehensive Income was as follows (in thousands):



		Three Months Ended
		March 31, 2012
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income
Interest rate swaps - unrealized	Unrealized gain (loss) on interest rate swaps, net	$	12,045
Interest rate swaps - realized	Interest expense	(3,205		)
		$	8,840



		Three Months Ended
		March 31, 2011
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income
Interest rate swaps - unrealized	Unrealized gain (loss) on interest rate swaps, net	$	5,465
Interest rate swaps - realized	Interest expense	(3,352		)
		$	2,113

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2012

Fair Value of Financial Instruments

FAIR VALUE OF FINANCIAL INSTRUMENTS

The estimated fair values of our financial instruments are as follows (in thousands) as of:



	March 31, 2012				December 31, 2011				March 31, 2011
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Cash and cash equivalents ^(a)	$	56,132	$	56,132	$	21,628	$	21,628	$	26,418	$	26,418
Restricted cash ^(a)	$	8,960	$	8,960	$	9,254	$	9,254	$	3,406	$	3,406
Total derivative assets ^(b)	$	18,758	$	18,758	$	20,554	$	20,554	$	8,996	$	8,996
Total derivative liabilities ^(b)	$	119,558	$	119,558	$	133,400	$	133,400	$	75,762	$	75,762
Notes payable ^(a)	$	225,000	$	225,000	$	345,000	$	345,000	$	287,000	$	287,000
Long-term debt, including current maturities ^(c)	$	1,280,993	$	1,439,724	$	1,282,882	$	1,464,289	$	1,189,084	$	1,260,539

____________


(a)	Carrying value approximates fair value due to short-term maturities and therefore is classified in Level 1 in the fair value hierarchy.


(b)	See Note 14 for information on classification within the fair value hierarchy.


(c)	Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

The following methods and assumptions were used to estimate the fair value of each class of our financial instruments.

Cash and Cash Equivalents

Included in cash and cash equivalents is cash, overnight repurchase agreement accounts, money market funds and term deposits. As part of our cash management process, excess operating cash is invested in overnight repurchase agreements with our bank. Repurchase agreements are not deposits and are not insured by the U.S. Government, the FDIC or any other government agency and involve investment risk including possible loss of principal. We believe however, the market risk arising from holding these financial instruments is minimal. The carrying amount for cash and cash equivalents approximates fair value due to the short-term maturity of these instruments.

Restricted Cash

Restricted cash represents amounts required by Black Hills Wyoming project financing agreements. Of this total, $4.8 million, $0.0 million and $0.0 million for March 31, 2012, December 31, 2011 and March 31, 2011, respectively, were held in uninsured term deposits held at a Canadian bank.

Derivative Financial Instruments

These instruments are carried at fair value. These inputs include unadjusted quoted prices where available, prices published by various third party providers, and, when necessary, internally developed adjustments. In many cases, the internally developed prices are corroborated with external sources. Certain Company transactions take place in markets with limited liquidity and limited price visibility. Descriptions of the various instruments we use and the valuation methods employed are included in Notes 13 and 14.

Notes Payable

The carrying amounts of our notes payable approximate fair value due to their variable interest rates with short reset periods.

Long-term Debt

Our debt instruments are marked to fair value using the market valuation approach. The fair value for our fixed rate debt instruments is estimated based on quoted market prices and yields for debt instruments having similar maturities and debt ratings. The carrying amounts of our variable rate debt approximate fair value due to the variable interest rates with short reset periods.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B
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-Number 107
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-Number 107
-Paragraph 15B
-Subparagraph a, b
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-Number 107
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Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES There have been no significant changes to commitments and contingencies from those previously disclosed in Note 19 of our Notes to the Consolidated Financial Statements in our 2011 Annual Report on Form 10-K.

The entire disclosure for commitments and contingencies.

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-Number 5
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-Name Accounting Standards Codification
-Topic 210
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Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]

Discontinued Operations

3 Months Ended

Mar. 31, 2012

Discontinued Operations [Abstract]

DISCONTINUED OPERATIONS

On February 29, 2012, we sold the outstanding stock of our Energy Marketing segment, Enserco Energy Inc. The transaction was completed through a stock purchase agreement and certain other ancillary agreements. Net cash proceeds were approximately $166.3 million, subject to final post-closing adjustments that are expected to be settled during the second quarter of 2012. The proceeds represent $108.8 million received from Twin Eagle and $57.5 million cash retained from Enserco prior to closing. We recorded an after-tax loss on sale of $1.6 million, including transaction related costs net of tax of $2.2 million.

The accompanying Condensed Consolidated Financial Statements have been classified to reflect Enserco as discontinued operations. For comparative purposes, all prior periods presented have been restated to reflect the classification.

Operating results of the Energy Marketing segment included in Income (loss) from discontinued operations, net of tax on the accompanying Condensed Consolidated Statements of Income and Comprehensive Income were as follows (in thousands):



	For the Three Months Ended
	March 31, 2012			March 31, 2011

Revenue	$	(604	)	$	2,465

Pre-tax income (loss) from discontinued operations	(5,836		)	(3,174		)
Pre-tax gain (loss) on sale	(2,453		)	—
Income tax (expense) benefit	2,805			1,016

Income (loss) from discontinued operations, net of tax	$	(5,484	)	$	(2,158	)

Indirect corporate costs and inter-segment interest expenses totaling $1.6 million and $0.5 million for the three months ended March 31, 2012 and March 31, 2011, respectively, are reclassified from the Energy Marketing segment to the Corporate segment in continuing operations on the accompanying Condensed Consolidated Statements of Income and Comprehensive Income.

Net assets of the Energy Marketing segment included in Assets/Liabilities of discontinued operations in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands) as of:



	December 31, 2011			March 31, 2011
Other current assets	$	280,221		$	243,473
Derivative assets, current and non-current	52,859			45,432
Property, plant and equipment, net	5,828			4,750
Goodwill	1,435			1,435
Other non-current assets	508			631
Other current liabilities	(132,951		)	(129,706		)
Derivative liabilities, current and non-current	(26,084		)	(30,932		)
Other non-current liabilities	(14,894		)	(2,652		)
Net assets	$	166,922		$	132,431

The entire disclosure for the facts and circumstances leading to the completed or expected disposal, manner and timing of disposal, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the segment in which the disposal group was reported, and the classification (whether sold or classified as held for sale) and carrying value of the assets and liabilities comprising the disposal group. Includes all disposal groups, including those classified as components of the entity (discontinued operations).

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 144
-Paragraph 43-48
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2941-110230

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
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-Section 45
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information Suplemental Disclosures of Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2012

Supplemental Disclosure of Cash Flow Information



	Three Months Ended
	March 31, 2012			March 31, 2011
	(in thousands)
Non-cash investing activities from continuing operations—
Property, plant and equipment acquired with accrued liabilities	$	31,644		$	32,220
Capitalized assets associated with retirement obligations	$	2,826		$	—
Cash (paid) refunded during the period for continuing operations—
Interest (net of amounts capitalized)	$	(16,799	)	$	(11,572	)
Income taxes, net	$	(1,838	)	$	48

Materials, Supplies and Fuel Materials, Supplies and Fuel (Tables)

3 Months Ended

Mar. 31, 2012

Inventory, Net [Abstract]

Schedule of Inventory, current

The amounts of Materials, supplies and fuel included in the accompanying Condensed Consolidated Balance Sheets, by major classification, were as follows (in thousands) as of:



	March 31, 2012		December 31, 2011		March 31, 2011
Materials and supplies	$	44,361	$	40,838	$	34,129
Fuel - Electric Utilities	7,812		8,201		9,307
Natural gas in storage - gas utilities	11,063		35,025		2,199
Total materials, supplies and fuel	$	63,236	$	84,064	$	45,635

Accounts Receivable Accounts Receivable (Tables)

3 Months Ended

Mar. 31, 2012

Receivables [Abstract]

Summary of accounts receivables

Following is a summary of receivables (in thousands) as of:



	Accounts		Unbilled		Less Allowance for			Accounts
March 31, 2012	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	44,356	$	19,381	$	(585	)	$	63,152
Gas	44,287		18,502		(936		)	61,853
Oil and Gas	15,014		—		(105		)	14,909
Coal Mining	2,578		—		—			2,578
Power Generation	265		—		—			265
Corporate	1,230		—		—			1,230
Total	$	107,730	$	37,883	$	(1,626	)	$	143,987



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2011	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	42,773	$	21,151	$	(545	)	$	63,379
Gas	39,353		38,992		(1,011		)	77,334
Oil and Gas	11,282		—		(105		)	11,177
Coal Mining	4,056		—		—			4,056
Power Generation	282		—		—			282
Corporate	546		—		—			546
Total	$	98,292	$	60,143	$	(1,661	)	$	156,774



	Accounts		Unbilled		Less Allowance for			Accounts
March 31, 2011	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric	$	46,077	$	16,196	$	(728	)	$	61,545
Gas	58,665		21,620		(1,763		)	78,522
Oil and Gas	7,503		—		(161		)	7,342
Coal Mining	982		—		—			982
Power Generation	2,050		—		—			2,050
Corporate	1,083		—		—			1,083
Total	$	116,360	$	37,816	$	(2,652	)	$	151,524

Notes Payable Notes Payable (Tables)

3 Months Ended

Mar. 31, 2012

Schedule of Short-term Debt

We had the following short-term debt outstanding as of the Condensed Consolidated Balance Sheet dates (in thousands):



	March 31, 2012				December 31, 2011				March 31, 2011
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	75,000	$	41,200	$	195,000	$	43,700	$	187,000	$	51,000
Term Loan due 2011*	—		—		—		—		100,000		—
Term Loan due 2012	150,000		—		150,000		—		—		—
Total	$	225,000	$	41,200	$	345,000	$	43,700	$	287,000	$	51,000

______________

* The short-term loan was renegotiated to a longer term note, maturing in 2013.

Revolving Credit Facility, Existing [Member]

Credit Facility Covenants

Certain debt obligations require compliance with the following covenants at the end of each quarter (dollars in thousands).



	As of			Covenant
	March 31, 2012			Requirement
Consolidated Net Worth	$	1,224,692		$	899,024
Recourse Leverage Ratio	56.4		%	65.0		%

Earnings per Share Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2012

Earnings Per Share [Abstract]

Earnings Per Share Reconciliation

A reconciliation of share amounts used to compute earnings (loss) per share is as follows (in thousands):



	Three Months Ended March 31,
	2012		2011

Income (loss) from continuing operations	$	35,271	$	29,068

Weighted average shares - basic	43,731		39,059
Dilutive effect of:
Restricted stock	147		132
Stock options	18		17
Equity forward instruments	—		460
Other dilutive effects	73		93
Weighted average shares - diluted	43,969		39,761

Antidilutive Securities Excluded from Computation of Earnings Per Share

The following outstanding securities were not included in the computation of diluted earnings per share as their effect would have been anti-dilutive (in thousands):



	Three Months Ended March 31,
	2012	2011
Stock options	127	83
Restricted stock	31	7
Other stock	16	—
Anti-dilutive shares	174	90

Comprehensive Income (Loss) Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2012

Other Comprehensive (Loss) Income [Abstract]

Components of Comprehensive Income (loss)

The following table presents the components of our comprehensive income (loss) (in thousands):



Three Months Ended March 31, 2012	Pre-tax Amount			Tax (Expense) Benefit		Net-of-tax Amount
Fair value adjustment of derivatives designated as cash flow hedges	$	521		$	55	$	576
Reclassification adjustments of cash flow hedges settled and included in net income (loss)	(1,187		)	445		(742		)
Other comprehensive income (loss)	$	(666	)	$	500	$	(166	)



Three Months Ended March 31, 2011	Pre-tax Amount			Tax (Expense) Benefit			Net-of-tax Amount
Fair value adjustment of derivatives designated as cash flow hedges	$	(3,785	)	$	1,637		$	(2,148	)
Reclassification adjustments of cash flow hedges settled and included in net income (loss)	861			(292		)	569
Other comprehensive income (loss)	$	(2,924	)	$	1,345		$	(1,579	)

Balances by classification included within Accumulated Other Comprehensive Income (Loss)

Balances by classification included within Accumulated other comprehensive income (loss) on the accompanying Condensed Consolidated Balance Sheets are as follows (in thousands):



	Derivatives Designated as Cash Flow Hedges			Employee Benefit Plans			Total
Balance as of December 31, 2011	$	(13,802	)	$	(19,076	)	$	(32,878	)
Other comprehensive income (loss)	(166		)	—			(166		)
Ending Balance March 31, 2012	$	(13,968	)	$	(19,076	)	$	(33,044	)

	Derivatives Designated as Cash Flow Hedges			Employee Benefit Plans			Total
Balance as of December 31, 2010	$	(12,439	)	$	(11,142	)	$	(23,581	)
Other comprehensive income (loss)	(1,579		)	—			(1,579		)
Ending Balance March 31, 2011	$	(14,018	)	$	(11,142	)	$	(25,160	)

Employee Benefit Plans Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2012

Contributions to Healthcare and Supplemental Plans

Contributions to the Defined Benefit Plans will be made in cash and contributions to the Healthcare Plans and the Supplemental Plans are expected to be made in the form of benefit payments. Contributions are as follows (in thousands):



	Contributions Made
	Three Months Ended March 31, 2012		Additional Contributions Anticipated for 2012		Contributions Anticipated for 2013
Defined Benefit Pension Plans	$	25,000	$	—	$	4,500
Non-pension Defined Benefit Postretirement Healthcare Plans	$	1,063	$	3,188	$	4,380
Supplemental Non-qualified Defined Benefit Plans	$	278	$	833	$	1,090

Pension Plans, Defined Benefit

Components of net periodic benefit cost

The components of net periodic benefit cost for the Pension Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012			2011
Service cost	$	1,430		$	1,355
Interest cost	3,687			3,732
Expected return on plan assets	(4,084		)	(4,239		)
Prior service cost	22			25
Net loss (gain)	2,408			1,135
Net periodic benefit cost	$	3,463		$	2,008

Non-pension Postretirement Healthcare Plans, Defined Benefit

Components of net periodic benefit cost

The components of net periodic benefit cost for the Healthcare Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012			2011
Service cost	$	402		$	375
Interest cost	523			542
Expected return on plan assets	(19		)	(41		)
Prior service cost (benefit)	(125		)	(120		)
Net loss (gain)	222			169
Net periodic benefit cost	$	1,003		$	925

Supplemental Non-qualified Plans, Defined Benefit

Components of net periodic benefit cost

The components of net periodic benefit cost for the Supplemental Plans were as follows (in thousands):



	Three Months Ended March 31,
	2012		2011
Service cost	$	246	$	257
Interest cost	331		324
Prior service cost	1		1
Net loss (gain)	202		127
Net periodic benefit cost	$	780	$	709

Segment Reporting Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2012

Segment Reporting Information, Additional Information [Abstract]

Segment information included in Condensed Consolidated Statements of Income

Segment information included in the accompanying Condensed Consolidated Statements of Income and Comprehensive Income and Condensed Consolidated Balance Sheets was as follows (in thousands):



Three Months Ended March 31, 2012	External Operating Revenues		Intercompany Operating Revenues			Income (Loss) from Continuing Operations
Utilities:
Electric	$	156,133	$	3,036		$	8,746
Gas	180,522		—			15,207
Non-regulated Energy:
Oil and Gas	21,645		—			13
Power Generation	1,178		18,449			6,914
Coal Mining	6,373		8,616			1,000
Corporate ^(a)(b)	—		—			3,391
Intercompany eliminations	—		(30,101		)	—
Total	$	365,851	$	—		$	35,271



Three Months Ended March 31, 2011	External Operating Revenues		Intercompany Operating Revenues			Income (Loss) from Continuing Operations
Utilities:
Electric	$	144,430	$	3,839		$	10,249
Gas	230,266		—			19,263
Non-regulated Energy:
Oil and Gas	17,906		—			(715		)
Power Generation	687		6,933			1,186
Coal Mining	7,614		7,881			(1,298		)
Corporate ^(a)(b)	—		—			451
Intercompany eliminations	—		(18,721		)	(68		)
Total	$	400,903	$	(68	)	$	29,068

____________


(a)	Income (loss) from continuing operations includes $7.8 million and $3.6 million net after-tax mark-to-market gain on interest rate swaps for the three months ended March 31, 2012 and March 31, 2011, respectively.


(b)	Certain direct corporate costs and inter-segment interest expense previously allocated to our Energy Marketing segment were not classified as discontinued operations but were included in the Corporate segment. See Note 17 for further information.

Segment information included in Condensed Consolidated Balance Sheets



Total Assets (net of inter-company eliminations)	March 31, 2012		December 31, 2011		March 31, 2011
Utilities:
Electric^(a)	$	2,268,524	$	2,254,914	$	1,868,600
Gas	717,185		746,444		683,927
Non-regulated Energy:
Oil and Gas	430,851		425,970		355,357
Power Generation^(a)	128,225		129,121		336,827
Coal Mining	87,139		88,704		94,416
Corporate ^(b)	176,012		141,079		94,499
Discontinued operations ^(c)	—		340,851		295,724
Total assets	$	3,807,936	$	4,127,083	$	3,729,350

____________


(a)	The PPA under which the new generating facility was constructed at our Pueblo Airport Generation site by Colorado IPP to support Colorado Electric customers is accounted for as a capital lease. Therefore, commencing December 31, 2011, assets previously at Power Generation are now accounted for at Colorado Electric under accounting for a capital lease.

(b) Assets of the Corporate segment were restated due to deferred taxes that were not classified as discontinued operations.

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

Risk Management Activities Risk Management (Tables)

3 Months Ended

Mar. 31, 2012

Financing Activities

Interest rate swaps and related balances

Our interest rate swaps and related balances were as follows (dollars in thousands) as of:



	March 31, 2012						December 31, 2011						March 31, 2011
	Designated Interest Rate Swaps			De-designated Interest Rate Swaps*			Designated Interest Rate Swaps			De-designated Interest Rate Swaps*			Designated Interest Rate Swaps			De-designated Interest Rate Swaps*
Notional	$	150,000		$	250,000		$	150,000		$	250,000		$	150,000		$	250,000
Weighted average fixed interest rate	5.04		%	5.67		%	5.04		%	5.67		%	5.04		%	5.67		%
Maximum terms in years	4.75			1.75			5.00			2.00			5.75			0.75
Derivative liabilities, current	$	6,777		$	66,708		$	6,513		$	75,295		$	6,769		$	48,515
Derivative liabilities, non-current	$	18,441		$	17,237		$	20,363		$	20,696		$	12,955		$	—
Pre-tax accumulated other comprehensive income (loss)	$	(25,218	)	$	—		$	(26,876	)	$	—		$	(19,724	)	$	—
Pre-tax gain (loss)	$	—		$	12,045		$	—		$	(42,010	)	$	—		$	5,465
Cash collateral receivable (payable)	$	—		$	—		$	—		$	—		$	—		$	—

_____________


*	Maximum terms in years reflect the amended early termination dates. If the early termination dates are not extended, the swaps will require cash settlement based on the swap value on the termination date. If extended, de-designated swaps totaling $100 million terminate in 7 years and de-designated swaps totaling $150 million terminate in 17 years.

Oil and Gas [Member] | Oil and Gas Exploration and Production

Cash flow heding instruments included in financial statements

We had the following derivatives and related balances (dollars in thousands) as of:



	March 31, 2012					December 31, 2011					March 31, 2011
	Crude Oil Swaps/ Options			Natural Gas Swaps		Crude Oil Swaps/ Options			Natural Gas Swaps		Crude Oil Swaps/ Options			Natural Gas Swaps
Notional ^(a)	522,000			5,001,750		528,000			5,406,250		487,500			5,974,800
Maximum terms in years ^(b)	1.25			1.50		1.25			1.75		1.00			0.25
Derivative assets, current	$	406		$	8,256	$	729		$	8,010	$	108		$	6,649
Derivative assets, non-current	$	46		$	808	$	771		$	1,148	$	—		$	975
Derivative liabilities, current	$	2,904		$	—	$	2,559		$	—	$	4,688		$	—
Derivative liabilities, non-current	$	1,084		$	—	$	811		$	7	$	2,678		$	157
Pre-tax accumulated other comprehensive income (loss)	$	(3,566	)	$	9,064	$	(1,928	)	$	9,152	$	(7,613	)	$	7,467
Revenue ^(c)	$	30		$	—	$	58		$	—	$	355		$	—

____________


(a)	Crude oil in Bbls, gas in MMBtus


(b)	Refers to the term of the derivative instrument. Assets and liabilities are classified as current or non-current based on the term of the hedged transaction and the corresponding settlement of the derivative instruments.


(c)	Represents the amortization of put premiums

Utilities Group [Member] | Regulated Utilities - Gas Hedges

Cash flow heding instruments included in financial statements

We had the following derivative balances related to the hedges in our Utilities (in thousands) as of:



	March 31, 2012		December 31, 2011		March 31, 2011
Derivative assets, current	$	9,215	$	9,844	$	1,056
Derivative assets, non-current	$	27	$	52	$	209
Derivative liabilities, non-current	$	6,407	$	7,156	$	—
Net unrealized gain (loss) included in Regulatory assets or liabilities	$	15,223	$	17,556	$	2,455
Included in Derivatives:
Cash collateral receivable (payable)	$	17,651	$	19,416	$	3,720
Option premiums and commissions	$	407	$	880	$	—

Contract or notional amounts and terms of marketing activities and derivative commodity instruments

The contract or notional amounts and terms of the natural gas derivative commodity instruments held at our Utilities were as follows as of:



	March 31, 2012		December 31, 2011		March 31, 2011
	Notional (MMBtus)	Latest Expiration (months)	Notional (MMBtus)	Latest Expiration (months)	Notional (MMBtus)	Latest Expiration (months)
Natural gas futures purchased	11,550,000	81	14,310,000	84	4,680,000	24
Natural gas options purchased	670,000	12	1,720,000	3	—	—
Natural gas basis swaps purchased	7,640,000	81	7,160,000	60	—	—

Fair Value Measurements Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2012

Fair value assets and liabilities measured on recurring basis

The following tables set forth by level within the fair value hierarchy our assets and liabilities that were accounted for at fair value on a recurring basis (in thousands):



	As of March 31, 2012
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	404		$	—	$	—	$	—	$	404
Basis Swaps -- Oil	—		48			—		—		—		48
Options -- Gas	—		—			—		—		—		—
Basis Swaps -- Gas	—		9,064			—		—		—		9,064
Commodity derivatives — Utilities	—		(8,412		)	3		—		17,651		9,242
Repurchase agreement ^(a)	43,128		—			—		—		—		43,128
Money market funds and term deposits ^(a)	12,791		—			—		—		—		12,791
Total	$	55,919	$	1,104		$	3	$	—	$	17,651	$	74,677

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	1,347		$	—	$	—	$	—	$	1,347
Basis Swaps -- Oil	—		2,641			—		—		—		2,641
Options -- Gas	—		—			—		—		—		—
Basis Swaps -- Gas	—		—			—		—		—		—
Commodity derivatives — Utilities	—		6,359			48		—		—		6,407
Interest rate swaps	—		109,163			—		—		—		109,163
Total	$	—	$	119,510		$	48	$	—	$	—	$	119,558

______________

(a) Level 1 assets and liabilities and described at Note 15.



	As of December 31, 2011
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas	$	—	$	9,885		$	768	$	5	$	—	$	10,658
Commodity derivatives —Utilities	—		(9,520		)	—		—		19,416		9,896
Money market funds	6,005		—			—		—		—		6,005
Total	$	6,005	$	365		$	768	$	5	$	19,416	$	26,559

Liabilities:
Commodity derivatives — Oil and Gas	$	—	$	2,207		$	1,165	$	5	$	—	$	3,377
Commodity derivatives — Utilities	—		7,156			—		—		—		7,156
Interest rate swaps	—		122,867			—		—		—		122,867
Total	$	—	$	132,230		$	1,165	$	5	$	—	$	133,400



	As of March 31, 2011
	Level 1		Level 2			Level 3		Counterparty Netting		Cash Collateral		Total
Assets:
Commodity derivatives — Oil and Gas	$	—	$	7,626		$	106	$	—	$	—	$	7,732
Commodity derivatives — Utilities	—		(2,455		)	—		—		3,720		1,265
Money market funds	9,050		—			—		—		—		9,050
Total	$	9,050	$	5,171		$	106	$	—	$	3,720	$	18,047

Liabilities:
Commodity derivatives — Oil and Gas	$	—	$	7,523		$	—	$	—	$	—	$	7,523
Commodity derivatives — Utilities	—		—			—		—		—		—
Interest rate swaps	—		68,239			—		—		—		68,239
Total	$	—	$	75,762		$	—	$	—	$	—	$	75,762

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Table Text Block]

The following table presents the quantitative information about level 3 fair value measurements (dollars shown in thousands):



	Fair Value at		Valuation	Unobservable	Range (Weighted
	March 31, 2012		Technique	Input	Average)
ASSETS
Commodity derivatives - Utilities^(a)	$	3	Independent price quotes	Long-term natural gas prices	Not applicable

LIABILITIES
Commodity derivatives - Utilities^(a)	$	48	Independent price quotes	Long-term natural gas prices	Not applicable

______________________

(a)

Changes in level 3 recurring fair value

The following tables present the changes in Level 3 recurring fair value for the three months ended March 31, 2012 and 2011, respectively (in thousands):



	Three Months Ended March 31, 2012
Assets:	Commodity Derivatives -- Oil			Commodity Derivatives -- Gas		Commodity Derivatives -- Utilities		Total
Balances as of beginning of period	$	768		$	—	$	—	$	768
Total gain (loss) included in revenue	—			—		—		—
Total gain (loss) included in AOCI	(360		)	—		—		(360		)
Purchases	—			—		3		3
Issuances	—			—		—		—
Settlements	(4		)	—		—		(4		)
Transfers into level 3^(a)	—			—		—		—
Transfers out of level 3^(b)(c)	(404		)	—		—		(404		)
Balances at end of period	$	—		$	—	$	3	$	3

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	—		$	—	$	3	$	3



	Three Months Ended March 31, 2012
Liabilities:	Commodity Derivatives -- Oil			Commodity Derivatives -- Gas		Commodity Derivatives -- Utilities		Total
Balances as of beginning of period	$	1,165		$	—	$	—	$	1,165
Total gain (loss) included in revenue	—			—		—		—
Total gain (loss) included in AOCI	182			—		—		182
Purchases	—			—		48		48
Issuances	—			—		—		—
Settlements	—			—		—		—
Transfers into level 3^(a)	—			—		—		—
Transfers out of level 3^(b)(c)	(1,347		)	—		—		(1,347		)
Balances at end of period	$	—		$	—	$	48	$	48

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	—		$	—	$	48	$	48



	Three Months Ended March 31, 2011
	Commodity Derivatives
Balance as of beginning of period	$	266
Unrealized losses	(160		)
Unrealized gains	—
Settlements	—
Transfers into level 3^(a)	—
Transfers out of level 3^(b)	—
Balance at end of period	$	106

Changes in unrealized gains (losses) relating to instruments still held as of period-end	$	(159	)

____________


(a)	Transfers into Level 3 would occur when significant inputs used to value the derivative instruments become less observable such as a significant decrease in the frequency and volume in which the instrument is traded, negatively impacting the availability of observable pricing inputs.


(b)	Transfers out of Level 3 would occur when the significant inputs become more observable such as the time between the valuation date and the delivery date of a transaction becomes shorter, positively impacting the availability of observable pricing inputs.

Fair Value Hedging

Fair value and balance sheet classification of derivative instruments

The following tables present the fair value and balance sheet classification of our derivative instruments (in thousands):



As of March 31, 2012
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	8,662	$	—
Commodity derivatives	Derivative assets — non-current	854		—
Commodity derivatives	Derivative liabilities — current	—		2,904
Commodity derivatives	Derivative liabilities — non-current	—		1,084
Interest rate swaps	Derivative liabilities — current	—		6,777
Interest rate swaps	Derivative liabilities — non-current	—		18,441
Total derivatives designated as hedges		$	9,516	$	29,206

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	8,436
Commodity derivatives	Derivative assets — non-current	—		(27		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		6,407
Interest rate swaps	Derivative liabilities — current	—		66,708
Interest rate swaps	Derivative liabilities — non-current	—		17,237
Total derivatives not designated as hedges		$	—	$	98,761



As of December 31, 2011
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	8,739	$	—
Commodity derivatives	Derivative assets — non-current	1,919		—
Commodity derivatives	Derivative liabilities — current	—		2,559
Commodity derivatives	Derivative liabilities — non-current	—		818
Interest rate swaps	Derivative liabilities — current	—		6,513
Interest rate swaps	Derivative liabilities — non-current	—		20,363
Total derivatives designated as hedges		$	10,658	$	30,253

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	9,572
Commodity derivatives	Derivative assets — non-current	—		(52		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		7,156
Interest rate swaps	Derivative liabilities — current	—		75,295
Interest rate swaps	Derivative liabilities — non-current	—		20,696
Total derivatives not designated as hedges		$	—	$	112,667



As of March 31, 2011
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	6,757	$	—
Commodity derivatives	Derivative assets — non-current	975		—
Commodity derivatives	Derivative liabilities — current	—		4,688
Commodity derivatives	Derivative liabilities — non-current	—		2,835
Interest rate swaps	Derivative liabilities — current	—		6,769
Interest rate swaps	Derivative liabilities — non-current	—		12,955
Total derivatives designated as hedges		$	7,732	$	27,247

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	2,665
Commodity derivatives	Derivative assets — non-current	—		(209		)
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		—
Interest rate swaps	Derivative liabilities — current	—		48,515
Interest rate swaps	Derivative liabilities — non-current	—		—
Total derivatives not designated as hedges		$	—	$	50,971

Cash Flow Hedging [Member]

Cash flow hedges included in Accumulated Other Comprehensive Income

The impact of cash flow hedges on our Condensed Consolidated Statements of Income and Comprehensive Income was as follows (in thousands):



Three Months Ended March 31, 2012
Derivatives in Cash Flow Hedging Relationships	Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)			Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)	Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)
Interest rate swaps	$	(762	)	Interest expense	$	(1,822	)		$	—
Commodity derivatives	1,283			Revenue	3,009				—
Total	$	521			$	1,187			$	—



Three Months Ended March 31, 2011
Derivatives in Cash Flow Hedging Relationships	Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)			Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)	Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)			Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)
Interest rate swaps	$	298		Interest expense	$	(1,892	)		$	—
Commodity derivatives	(4,083		)	Revenue	1,031				—
Total	$	(3,785	)		$	(861	)		$	—

Derivatives Not Designated as Hedge Instruments

Gains and losses recognized in income

The impact of derivative instruments that have not been designated as hedging instruments on our Condensed Consolidated Statements of Income and Comprehensive Income was as follows (in thousands):



		Three Months Ended
		March 31, 2012
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income
Interest rate swaps - unrealized	Unrealized gain (loss) on interest rate swaps, net	$	12,045
Interest rate swaps - realized	Interest expense	(3,205		)
		$	8,840



		Three Months Ended
		March 31, 2011
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income
Interest rate swaps - unrealized	Unrealized gain (loss) on interest rate swaps, net	$	5,465
Interest rate swaps - realized	Interest expense	(3,352		)
		$	2,113

Fair Value of Financial Instruments Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2012

Fair Value of Financial Instruments [Abstract]

Fair value of financial instruments

The estimated fair values of our financial instruments are as follows (in thousands) as of:



	March 31, 2012				December 31, 2011				March 31, 2011
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Cash and cash equivalents ^(a)	$	56,132	$	56,132	$	21,628	$	21,628	$	26,418	$	26,418
Restricted cash ^(a)	$	8,960	$	8,960	$	9,254	$	9,254	$	3,406	$	3,406
Total derivative assets ^(b)	$	18,758	$	18,758	$	20,554	$	20,554	$	8,996	$	8,996
Total derivative liabilities ^(b)	$	119,558	$	119,558	$	133,400	$	133,400	$	75,762	$	75,762
Notes payable ^(a)	$	225,000	$	225,000	$	345,000	$	345,000	$	287,000	$	287,000
Long-term debt, including current maturities ^(c)	$	1,280,993	$	1,439,724	$	1,282,882	$	1,464,289	$	1,189,084	$	1,260,539

____________


(a)	Carrying value approximates fair value due to short-term maturities and therefore is classified in Level 1 in the fair value hierarchy.


(b)	See Note 14 for information on classification within the fair value hierarchy.


(c)	Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13467-108611

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13476-108611

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Condensed Statement of Income [Member]

Discontinued Operations Discontinued Operations (Tables)

3 Months Ended

Mar. 31, 2012

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]



	For the Three Months Ended
	March 31, 2012			March 31, 2011

Revenue	$	(604	)	$	2,465

Pre-tax income (loss) from discontinued operations	(5,836		)	(3,174		)
Pre-tax gain (loss) on sale	(2,453		)	—
Income tax (expense) benefit	2,805			1,016

Income (loss) from discontinued operations, net of tax	$	(5,484	)	$	(2,158	)

Condensed Balance Sheet [Member]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Net assets of the Energy Marketing segment included in Assets/Liabilities of discontinued operations in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands) as of:



	December 31, 2011			March 31, 2011
Other current assets	$	280,221		$	243,473
Derivative assets, current and non-current	52,859			45,432
Property, plant and equipment, net	5,828			4,750
Goodwill	1,435			1,435
Other non-current assets	508			631
Other current liabilities	(132,951		)	(129,706		)
Derivative liabilities, current and non-current	(26,084		)	(30,932		)
Other non-current liabilities	(14,894		)	(2,652		)
Net assets	$	166,922		$	132,431

Tabular disclosure of disposal groups, which may include the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the classification and carrying value of the assets and liabilities comprising the disposal group, and the segment in which the disposal group was reported. Also may include the amount of adjustments to amounts previously reported in discontinued operations such as resolution of contingencies arising from the disposal transaction or the operations of the component prior to disposal.

Management's Statement Management's Statement (Details)	Feb. 29, 2012
Energy Marketing [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Significant Acquisitions and Disposals, Date of Transaction for Acquisition or Disposal	Feb. 29, 2012

Supplemental Disclosure of Cash Flow Information Supplemental Disclosures of Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Non-cash investing activities
Property, plant and equipment acquired with accrued liabilities	$ 31,644	$ 32,220
Non-cash Revision to Capitalized Asset Retirement Costs	2,826	0
Cash (paid) refunded during the period for
Interest (net of amounts capitalized)	(16,799)	(11,572)
Income taxes, net	$ (1,838)	$ 48

Materials, Supplies and Fuel Materials, Supplies and Fuel (Details) - USD ($) $ in Thousands	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Materials and supplies	$ 44,361	$ 40,838	$ 34,129
Natural gas in storage - gas utilities	11,063	35,025	2,199
Materials, supplies and fuel	63,236	84,064	45,635
Electric Utilities [Member]
Fuel - Electric Utilities	$ 7,812	$ 8,201	$ 9,307

Accounts Receivable Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	$ (1,626)	$ (1,661)	$ (2,652)
Accounts receivable, net	143,987	156,774	151,524
Electric Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	(585)	(545)	(728)
Accounts receivable, net	63,152	63,379	61,545
Gas Utilities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	(936)	(1,011)	(1,763)
Accounts receivable, net	61,853	77,334	78,522
Oil and Gas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	(105)	(105)	(161)
Accounts receivable, net	14,909	11,177	7,342
Coal Mining
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	0	0	0
Accounts receivable, net	2,578	4,056	982
Power Generation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	0	0	0
Accounts receivable, net	265	282	2,050
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	0	0	0
Accounts receivable, net	1,230	546	1,083
Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	107,730	98,292	116,360
Billed Revenues [Member] \| Electric Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	44,356	42,773	46,077
Billed Revenues [Member] \| Gas Utilities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	44,287	39,353	58,665
Billed Revenues [Member] \| Oil and Gas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	15,014	11,282	7,503
Billed Revenues [Member] \| Coal Mining
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	2,578	4,056	982
Billed Revenues [Member] \| Power Generation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	265	282	2,050
Billed Revenues [Member] \| Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	1,230	546	1,083
Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	37,883	60,143	37,816
Unbilled Revenues [Member] \| Electric Utilities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	19,381	21,151	16,196
Unbilled Revenues [Member] \| Gas Utilities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	18,502	38,992	21,620
Unbilled Revenues [Member] \| Oil and Gas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	0	0	0
Unbilled Revenues [Member] \| Coal Mining
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	0	0	0
Unbilled Revenues [Member] \| Power Generation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	0	0	0
Unbilled Revenues [Member] \| Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	$ 0	$ 0	$ 0

Notes Payable Line of Credit Facility (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

$ 225,000

$ 345,000

$ 287,000

Consolidated Net Worth, Actual

41,200

43,700

51,000

1,224,692

1,209,336

1,113,147

Line of Credit, Covenant Requirement, Consolidated Net Worth, Minimum

$ 899,024

Recourse Leverage Ratio

56.40%

Line of Credit, Covenant Requirement, Recourse Leverage Ratio

65.00%

Line of Credit [Member]

$ 75,000

195,000

187,000

Line of Credit Facility, Current Borrowing Capacity

41,200

43,700

51,000

$ 500,000

Line of Credit Facility, Expiration Date

2/1/2017

Line of Credit Facility, Maximum Borrowing Capacity

$ 750,000

Line of Credit Facility, Commitment Fee Percentage

0.25%

Deferred Financing Costs Remaining on Balance Sheet

$ 2,800

Write off of Deferred Debt Issuance Cost

$ 1,500

Line of Credit [Member] | Base Rate Option

Line of Credit Facility, Interest Rate at Period End

0.50%

Line of Credit [Member] | Eurodollar Option

Line of Credit Facility, Interest Rate at Period End

1.50%

Line of Credit [Member] | Letter of Credit [Member]

Line of Credit Facility, Interest Rate at Period End

1.50%

Corporate Term Loan due June 2012 [Member] | Loans Payable [Member]

$ 150,000

150,000

Corporate Term Loan due in 2013 [Member] | Loans Payable [Member]

100,000

^[1]

$ 0

[1]	The short-term loan was renegotiated to a longer term note, maturing in 2013.

Long-Term Debt Long-term Debt (Details) - Electric Utilities [Member] - Polution Control Revenue Bonds Due 2014 [Member] - USD ($) $ in Millions		3 Months Ended
	May 15, 2012	Mar. 31, 2012
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		Oct. 01, 2014
Early Repayment of Subordinated Debt	$ 6.5
Debt Instrument, Early Repayment Date	May 15, 2012

Earnings per Share Reconcilation of Basic to Dilutive Shares (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (loss) from continuing operations	$ 35,271	$ 29,068
Weighted average shares - basic	43,731	39,059
Dilutive effect of:
Incremental Common Shares Attributable To Share Based Payment Arrangements, Restricted Stock and Restricted Stock Units	147	132
Incremental Common Shares Attributable To Share Based Payment Arrangements, Options	18	17
Equity forward issuance	0	460
Other Stock	73	93
Weighted average shares - diluted	43,969	39,761

This element represents the income or loss from continuing operations attributable to the parent which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 29
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph b(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=6921628&loc=SL4613673-111683

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.13)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6920599&loc=d3e1448-109256

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Weighted-Average Number of Common Shares Outstanding
-URI http://asc.fasb.org/extlink&oid=6528421

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Earnings per Share Anti-dilutive shares (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	174	90
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	127	83
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	31	7
Other Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	16	0

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 13, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Comprehensive Income (Loss) Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income (loss)	$ 29,787	$ 26,910
Other comprehensive income (loss), net of tax:
Fair value adjustment on derivatives designated as cash flow hedges	521	(3,785)
Reclassification adjustments on cash flow hedges settled and included in net income (loss)	(1,187)	861
Other Comprehensive Income (Loss), before Tax	(666)	(2,924)
Taxes on fair value adjustment on derivatives designated as cash flow hedges	55	1,637
Reclassification adjustment on cash flow hedges settled and included in net income (loss), tax	445	(292)
Other Comprehensive Income (Loss), Tax	500	1,345
Fair value adjustment on derivatives designated as cash flow hedges, net of tax	576	(2,148)
Reclassification adjustments on cash flow hedges settled and included in net income (loss), net of tax	(742)	569
Other comprehensive income (loss), net of tax	$ (166)	$ (1,579)

Comprehensive Income (Loss) Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss) total, period start	$ (32,878)	$ (23,581)
Other comprehensive income (loss), net of tax	(166)	(1,579)
Accumulated other comprehensive income (loss) total, period end	(33,044)	(25,160)
Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss) total, period start	(13,802)	(12,439)
Other comprehensive income (loss), net of tax	(166)	(1,579)
Accumulated other comprehensive income (loss) total, period end	(13,968)	(14,018)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss) total, period start	(19,076)	(11,142)
Other comprehensive income (loss), net of tax	0	0
Accumulated other comprehensive income (loss) total, period end	$ (19,076)	$ (11,142)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

Common Stock Equity Compensation (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2012 USD ($) years $ / shares shares	Mar. 31, 2011 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 12.2
Allocated Share-based Compensation Expense	$ 1.8	$ 2.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition \| years	2.3
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares	66,690
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	Jan. NaN, 2012
Performance Share Award, Percentage of Target, Minimum	0.00%
Performance Share Award, Percentage of Target, Maximum	200.00%
Performance Share Award Payout, Cash Percentage	50.00%
Performance Share Award Payout, Shares of Common Stock Percentage	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value \| $ / shares	$ 32.26
Short-term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period \| shares	3,690
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	$ 0.1
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period \| shares	139,550
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 4.9
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period \| shares	41,206
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price \| $ / shares	$ 28.28
Proceeds from Stock Options Exercised	$ 1.2
Cheyenne Light [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Debt Instrument, Covenant Description	Debt capitalization requirement of 0.60 to 1.00

Common Stock Dividend Reinvestment and Stock Purchase Plan (Details) - DRIP [Member]	3 Months Ended
	Mar. 31, 2012 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase, Percentage of Recent Average Market Price	100.00%
Stock Issued During Period, Shares, Dividend Reinvestment Plan	27,155
Weighted Average Price of Shares, Dividend Reinvestment Plan \| $ / shares	$ 33.20
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	426,109

Common Stock Dividend Restrictions Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Restricted cash	$ 8,960	$ 9,254	$ 3,406
Cheyenne Light [Member]
Debt Instrument, Covenant Description	Debt capitalization requirement of 0.60 to 1.00
Utilities Group [Member]
Amount of Restricted Net Assets for Subsidiaries	$ 81,400
Non Regulated Energy Group [Member]
Amount of Restricted Net Assets for Subsidiaries	100,000
Restricted Cash, Carrying Amount
Restricted cash	$ 8,960	$ 9,254	$ 3,406

Employee Benefit Plans Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,430	$ 1,355
Interest cost	3,687	3,732
Expected return on plan assets	(4,084)	(4,239)
Prior service cost	22	25
Net loss (gain)	2,408	1,135
Net periodic benefit cost	3,463	2,008
Contributions Made	25,000
Contributions Remaining in Current Fiscal Year	0
Contributions Anticipated in Next Fiscal Year	4,500
Non-pension Postretirement Healthcare Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	402	375
Interest cost	523	542
Expected return on plan assets	(19)	(41)
Prior service cost	(125)	(120)
Net loss (gain)	222	169
Net periodic benefit cost	1,003	925
Contributions Made	1,063
Contributions Remaining in Current Fiscal Year	3,188
Contributions Anticipated in Next Fiscal Year	4,380
Supplemental Non-qualified Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	246	257
Interest cost	331	324
Prior service cost	1	1
Net loss (gain)	202	127
Net periodic benefit cost	780	$ 709
Contributions Made	278
Contributions Remaining in Current Fiscal Year	833
Contributions Anticipated in Next Fiscal Year	$ 1,090

Segment Reporting Income Statement (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

$ 365,851

$ 400,903

(68)

Income (loss) from continuing operations

29,787

26,910

35,271

29,068

Increase Decrease in Fair Value of Derivative Instruments Not Designated as Hedging Instruments Net of Tax Included in Net Income

7,800

3,600

Electric Utilities [Member]

156,133

144,430

3,036

3,839

8,746

10,249

Gas Utilities

180,522

230,266

15,207

19,263

Oil and Gas [Member]

21,645

17,906

Power Generation [Member]

(715)

1,178

687

18,449

6,933

6,914

1,186

Coal Mining

6,373

7,614

8,616

7,881

Corporate Elimination [Member]

1,000

(1,298)

Intersegment Elimination [Member]

^[1]

3,391

451

^[2]

(30,101)

(18,721)

$ 0

$ (68)

[1]	Income (loss) from continuing operations includes $7.8 million and $3.6 million net after-tax mark-to-market gain on interest rate swaps for the three months ended March 31, 2012 and March 31, 2011, respectively.
[2]	Certain direct corporate costs and inter-segment interest expense previously allocated to our Energy Marketing segment were not classified as discontinued operations but were included in the Corporate segment. See Note 17 for further information.

Segment Reporting Assets (Details) - USD ($)
$ in Thousands

Mar. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Electric Utilities [Member]

$ 3,807,936

$ 4,127,083

$ 3,729,350

^[1]

2,268,524

2,254,914

1,868,600

Gas Utilities

717,185

746,444

683,927

Oil and Gas [Member]

Power Generation [Member]

430,851

425,970

355,357

^[1]

128,225

129,121

336,827

Coal Mining

Unallocated Amount to Segment [Member]

87,139

88,704

94,416

Discontinued Operation or Asset Disposal [Member]

176,012

141,079

94,499

^[2]

$ 0

$ 340,851

^[3]

$ 295,724

^[3]

[1]	The PPA under which the new generating facility was constructed at our Pueblo Airport Generation site by Colorado IPP to support Colorado Electric customers is accounted for as a capital lease. Therefore, commencing December 31, 2011, assets previously at Power Generation are now accounted for at Colorado Electric under accounting for a capital lease.
[2]	Assets of the Corporate segment were restated due to deferred taxes that were not classified as discontinued operations.
[3]	See Note 17 for further information relating to discontinued operations.

Risk Management Activities Risk Management (Details)
$ in Thousands

3 Months Ended

12 Months Ended

Mar. 31, 2012

USD ($)

Btu

bbl

Mar. 31, 2011

USD ($)

Btu

bbl

Dec. 31, 2011

USD ($)

Btu

bbl

$ 17,877

$ 7,812

$ 18,583

881

1,184

1,971

76,389

59,972

84,367

Unrealized Gain (Loss) on Derivatives

43,169

15,790

$ 49,033

$ (1,594)

$ (2,010)

Financing Activities | Interest Rate Swaps, Designated

Maximum Length of Time Hedged in Cash Flow Hedge (years)

4 years 9 months

5 years 9 months

5 years

$ 6,777

$ 6,769

$ 6,513

18,441

12,955

20,363

Collateral, included in other current assets

(25,218)

(19,724)

(26,876)

Derivative, Average Interest Rate

$ 150,000

5.04%

Gain (Loss) on Derivative Instruments, Net, Pretax

$ 0

Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net

(6,800)

Financing Activities | Interest Rate Swaps, Dedesignated

66,708

48,515

75,295

17,237

20,696

Latest Expiration, Maximum terms (months)

$ 0

1 year 9 months

9 months

2 years

Derivative, Collateral, Right to Reclaim Cash

$ 0

Derivative, Average Interest Rate

$ 250,000

5.67%

Gain (Loss) on Derivative Instruments, Net, Pretax

$ 12,045

$ 5,465

$ (42,010)

Financing Activities | Interest Rate Swaps, Dedesignated | Dedesignated Interest Rate Swap Expiring 2018 [Member]

7 years

Financing Activities | Interest Rate Swaps, Dedesignated | Dedesignated Interest Rate Swaps Expiring 2028 [Member]

$ 100,000

17 years

Oil and Gas [Member] | Oil and Gas Exploration and Production

$ 150,000

Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months

$ 4,300

Oil and Gas [Member] | Oil and Gas Exploration and Production | Natural Gas [Member] | Swap [Member]

Maximum Length of Time Hedged in Cash Flow Hedge (years)

5,001,750

^[1]

5,974,800

5,406,250

1 year 6 months

3 months

1 year 9 months

$ 8,256

$ 6,649

$ 8,010

808

975

1,148

157

Oil and Gas [Member] | Oil and Gas Exploration and Production | Crude Oil [Member] | Swaps and Options [Member]

9,064

7,467

9,152

Revenue

^[2]

$ 0

Derivative, Nonmonetary Notional Amount | bbl

522,000

^[1]

487,500

528,000

Maximum Length of Time Hedged in Cash Flow Hedge (years)

1 year 3 months

1 year

1 year 3 months

$ 406

$ 108

$ 729

771

2,904

4,688

2,559

1,084

2,678

811

Utilities Group [Member] | Regulated Utilities - Gas Hedges

(3,566)

(7,613)

(1,928)

Revenue

^[2]

355

9,215

1,056

9,844

209

Net Unrealized Gain (Loss) Included in Regulatory Assets

6,407

7,156

15,223

2,455

17,556

Cash collateral (receivable)/payable included in derivative assets/liabilities

17,651

3,720

19,416

Option Premium Included in Derivative Assets, Current

$ 407

$ 0

$ 880

Utilities Group [Member] | Regulated Utilities - Gas Hedges | Natural Gas [Member] | Commodity Option [Member] | Purchase Contract [Member]

670,000

1,720,000

Utilities Group [Member] | Regulated Utilities - Gas Hedges | Natural Gas [Member] | Future [Member] | Purchase Contract [Member]

12 months

3 months

11,550,000

4,680,000

14,310,000

Utilities Group [Member] | Regulated Utilities - Gas Hedges | Natural Gas [Member] | Basis Swap [Member] | Purchase Contract [Member]

81 months

24 months

84 months

7,640,000

7,160,000

Credit Risk [Member] | Interest Rate Swaps, Dedesignated

81 months

60 months

Potential Future Exposure on Credit Related Contingent Feature

$ 50,000

$ 20,000

[1]	Crude oil in Bbls, gas in MMBtus
[2]	Represents the amortization of put premiums.

Fair Value Measurements Fair Value Heirarchy Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Thousands

Mar. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Level 1

$ 6,005

$ 9,050

$ 55,919

6,005

9,050

Level 1 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Level 1 | Commodity Derivatives | Regulated Utilities Group

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Level 1 | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Level 2

1,104

365

5,171

Level 2 | Commodity Derivatives | Oil and Gas [Member]

119,510

132,230

75,762

9,885

7,626

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

2,207

7,523

Level 2 | Commodity Derivatives | Regulated Utilities Group

(8,412)

(9,520)

(2,455)

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

6,359

7,156

Level 2 | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

109,163

122,867

68,239

Level 3

768

106

Level 3 | Commodity Derivatives | Oil and Gas [Member]

1,165

768

106

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

1,165

Level 3 | Commodity Derivatives | Regulated Utilities Group

^[1]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

^[1]

Level 3 | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Counterparty Netting

Counterparty Netting | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Counterparty Netting | Commodity Derivatives | Regulated Utilities Group

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Counterparty Netting | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Cash Collateral [Member]

17,651

19,416

3,720

Cash Collateral [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Cash Collateral [Member] | Commodity Derivatives | Regulated Utilities Group

17,651

19,416

3,720

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Cash Collateral [Member] | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Estimate of Fair Value, Fair Value Disclosure [Member]

6,005

9,050

74,677

26,559

18,047

Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Oil and Gas [Member]

119,558

133,400

75,762

10,658

7,732

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

3,377

7,523

Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Regulated Utilities Group

9,242

9,896

1,265

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

6,407

7,156

Estimate of Fair Value, Fair Value Disclosure [Member] | Interest Rate Swap [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

109,163

$ 122,867

$ 68,239

Repurchase Agreements [Member] | Level 1

Repurchase Agreements [Member] | Level 2

43,128

Repurchase Agreements [Member] | Level 3

Repurchase Agreements [Member] | Counterparty Netting

Repurchase Agreements [Member] | Cash Collateral [Member]

Repurchase Agreements [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]

Interest-bearing Deposits [Member] | Level 1

43,128

Interest-bearing Deposits [Member] | Level 2

12,791

Interest-bearing Deposits [Member] | Level 3

Interest-bearing Deposits [Member] | Counterparty Netting

Interest-bearing Deposits [Member] | Cash Collateral [Member]

Interest-bearing Deposits [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]

Crude Oil [Member] | Commodity Option [Member] | Level 1 | Commodity Derivatives | Oil and Gas [Member]

12,791

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Commodity Option [Member] | Level 2 | Commodity Derivatives | Oil and Gas [Member]

404

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

1,347

Crude Oil [Member] | Commodity Option [Member] | Level 3 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Commodity Option [Member] | Counterparty Netting | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Commodity Option [Member] | Cash Collateral [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Commodity Option [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Oil and Gas [Member]

404

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

1,347

Crude Oil [Member] | Basis Swap [Member] | Level 1 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Basis Swap [Member] | Level 2 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

2,641

Crude Oil [Member] | Basis Swap [Member] | Level 3 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Basis Swap [Member] | Counterparty Netting | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Basis Swap [Member] | Cash Collateral [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Crude Oil [Member] | Basis Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

2,641

Natural Gas [Member] | Commodity Option [Member] | Level 1 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Commodity Option [Member] | Level 2 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Commodity Option [Member] | Level 3 | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Commodity Option [Member] | Counterparty Netting | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Commodity Option [Member] | Cash Collateral [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Commodity Option [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Basis Swap [Member] | Level 2 | Commodity Derivatives | Oil and Gas [Member]

9,064

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Basis Swap [Member] | Level 3 | Commodity Derivatives | Oil and Gas [Member]

Natural Gas [Member] | Basis Swap [Member] | Counterparty Netting | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Basis Swap [Member] | Cash Collateral [Member] | Commodity Derivatives | Oil and Gas [Member]

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Natural Gas [Member] | Basis Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commodity Derivatives | Oil and Gas [Member]

9,064

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

$ 0

[1]

Fair Value Measurements Changes in Level 3 Recurring Fair Value (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Dec. 31, 2011

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

$ 768

$ 0

(4)

^[1]

^[2],[3]

(404)

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

768

1,165

^[1]

^[2],[3]

(1,347)

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

1,165

Commodity Derivatives

(360)

Changes in unrealized gains relating to instruments still held as of quarter-end

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

182

Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income

Unobservable Input Reconciliation, net assets and liabilities [Abstract]

Net unrealized losess

$ (160)

Net unrealized gains

Net, Purchases, Sales, Issuances, Settlements

Net Transfers Into Level 3

^[1]

Net, Transfers out of Level 3

^[3]

Unobservable Inputs Reconciliation Net Value, balance at end of period

106

Change in Unrealized Gain (Loss) Included in Earnings

$ (159)

Oil and Gas [Member] | Crude Oil [Member] | Commodity Derivatives

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

768

(360)

(4)

^[1]

^[2],[3]

(404)

Changes in unrealized gains relating to instruments still held as of quarter-end

768

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

1,165

182

^[1]

^[2],[3]

(1,347)

Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income

1,165

Oil and Gas [Member] | Natural Gas [Member]

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

^[1]

^[2],[3]

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

^[1]

^[2],[3]

Oil and Gas [Member] | Natural Gas [Member] | Commodity Derivatives

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

Changes in unrealized gains relating to instruments still held as of quarter-end

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income

Utilities Group [Member] | Natural Gas [Member]

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

^[1]

^[2],[3]

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

^[1]

^[2],[3]

Utilities Group [Member] | Natural Gas [Member] | Commodity Derivatives

$ 0

Unobservable Inputs Reconciliation, Asset, Purchases, Sales, Issuances, Settlements [Abstract]

Changes in unrealized gains relating to instruments still held as of quarter-end

Unobservable Inputs Reconciliation, Liability, Purchases, Sales, Issuances, Settlements [Abstract]

Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) Included in Other Income

$ 48

[1]	Transfers into Level 3 would occur when significant inputs used to value the derivative instruments become less observable such as a significant decrease in the frequency and volume in which the instrument is traded, negatively impacting the availability of observable pricing inputs.
[2]	Previously, we utilized pricing methodologies developed by our Energy Marketing segment to value our Oil and Gas derivatives. Oil and Gas now obtains available observable inputs including quoted prices traded on active exchanges from multiple sources to value our options. Therefore, options in the Oil and Gas segment have been reclassified from Level 3 to Level 2.
[3]	Transfers out of Level 3 would occur when the significant inputs become more observable such as the time between the valuation date and the delivery date of a transaction becomes shorter, positively impacting the availability of observable pricing inputs.

Fair Value Measurements Fair Value Measures (Details) - USD ($)
$ in Thousands

Mar. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Derivatives Designated as Hedges

Derivative Asset, Fair Value, Net

$ 9,516

$ 10,658

$ 7,732

Derivative Liability, Fair Value, Net

29,206

30,253

27,247

Derivatives Not Designated as Hedges

Derivative Asset, Fair Value, Net

Derivative Liability, Fair Value, Net

98,761

112,667

50,971

Commodity Derivatives | Derivatives Designated as Hedges | Derivative Assets, Current

8,662

8,739

6,757

Commodity Derivatives | Derivatives Designated as Hedges | Derivative Assets, Noncurrent

854

1,919

975

Commodity Derivatives | Derivatives Designated as Hedges | Derivative Liabilities, Current

Commodity Derivatives | Derivatives Designated as Hedges | Derivative Liabilities, Noncurrent

2,904

2,559

4,688

Commodity Derivatives | Derivatives Not Designated as Hedges | Derivative Assets, Current

1,084

818

2,835

Commodity Derivatives | Derivatives Not Designated as Hedges | Derivative Assets, Noncurrent

8,436

9,572

2,665

Commodity Derivatives | Derivatives Not Designated as Hedges | Derivative Liabilities, Current

(27)

(52)

(209)

Commodity Derivatives | Derivatives Not Designated as Hedges | Derivative Liabilities, Noncurrent

Interest Rate Swap [Member] | Derivatives Designated as Hedges | Derivative Liabilities, Current

6,407

7,156

Interest Rate Swap [Member] | Derivatives Designated as Hedges | Derivative Liabilities, Noncurrent

6,777

6,513

6,769

Interest Rate Swap [Member] | Derivatives Not Designated as Hedges | Derivative Liabilities, Current

18,441

20,363

12,955

Interest Rate Swap [Member] | Derivatives Not Designated as Hedges | Derivative Liabilities, Noncurrent

66,708

75,295

48,515

Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Swap [Member]

17,237

20,696

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Utilities Group [Member] | Commodity Derivatives

Derivative Financial Instruments, Liabilities, Fair Value Disclosure

$ 48

^[1]

$ 0

[1]

Fair Value Measurements Hedging Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	$ 521	$ (3,785)
Amount of Reclassfied Gain/(Loss) from AOCI into Income (Effective Portion)	1,187	(861)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Cash Flow Hedging [Member] \| Commodity Derivatives
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	1,283	(4,083)
Cash Flow Hedging [Member] \| Commodity Derivatives \| Operating Revenue
Derivative Instruments, Gain (Loss)
Amount of Reclassfied Gain/(Loss) from AOCI into Income (Effective Portion)	3,009	1,031
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Cash Flow Hedging [Member] \| Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	(762)	298
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Cash Flow Hedging [Member] \| Interest Rate Swap [Member] \| Interest Expense
Derivative Instruments, Gain (Loss)
Amount of Reclassfied Gain/(Loss) from AOCI into Income (Effective Portion)	(1,822)	(1,892)
Derivatives Not Designated as Hedge Instruments
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) on Derivatives Recognized in Income	8,840	2,113
Derivatives Not Designated as Hedge Instruments \| Interest Rate Swap [Member] \| Interest Rate Swap - Unrealized (Loss) Gain
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) on Derivatives Recognized in Income	12,045	5,465
Derivatives Not Designated as Hedge Instruments \| Interest Rate Swap [Member] \| Interest Expense
Derivative Instruments, Gain (Loss)
Amount of Gain/(Loss) on Derivatives Recognized in Income	$ (3,205)	$ (3,352)

Fair Value of Financial Instruments Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands

Mar. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Cash and cash equivalents

$ 56,132

$ 21,628

$ 26,418

Restricted cash

8,960

9,254

3,406

Restricted Cash, Carrying Amount

225,000

345,000

287,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Cash and cash equivalents

56,132

21,628

26,418

Restricted cash

8,960

9,254

3,406

Derivative financial instruments - assets

^[1]

18,758

20,554

8,996

Derivative financial instruments - liabilities

^[1]

119,558

133,400

75,762

Long-term debt, including current maturities

225,000

345,000

287,000

1,280,993

1,282,882

1,189,084

Fair Value

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Cash and cash equivalents, fair value

^[2]

56,132

21,628

26,418

Restricted cash, fair value

^[2]

8,960

9,254

3,406

Derivative financial instruments - assets

^[1]

18,758

20,554

8,996

Derivative financial instruments - liabilities

^[1]

119,558

133,400

75,762

Notes payable, fair value

225,000

345,000

287,000

Long-term debt, including current maturities, fair value

^[3]

$ 1,439,724

$ 1,464,289

$ 1,260,539

[1]	See Note 14 for information on classification within the fair value hierarchy.
[2]	Carrying value approximates fair value due to short-term maturities and therefore is classified in Level 1 in the fair value hierarchy.
[3]	Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

Fair Value of Financial Instruments Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Power Generation [Member]
Restricted Cash - Guaranteed Investment Certificates	$ 4.8	$ 0.0	$ 0.0

Discontinued Operations Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended
	Feb. 29, 2012	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business		$ 108,837	$ 0
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax		1,600
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Overhead Of Discontinued Operations		1,600	500
Assets of Disposal Group, Including Discontinued Operation [Abstract]
Assets of Discontinued Operations		0	295,724	$ 340,851
Energy Marketing [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Significant Acquisitions and Disposals, Date of Transaction for Acquisition or Disposal	Feb. 29, 2012
Proceeds from Sales of Business, Affiliate and Productive Assets		166,300
Funds Retained, Sale of Business		57,500
Business Exit Costs		2,200
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Disposal Group, Including Discontinued Operation, Revenue		(604)	2,465
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax		(5,836)	(3,174)
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax		(2,453)	0
Discontinued Operation, Tax Effect of Discontinued Operation		2,805	1,016
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent		$ (5,484)	(2,158)
Assets of Disposal Group, Including Discontinued Operation [Abstract]
Assets of Disposal Group, Including Discontinued Operation, Current			243,473	280,221
Derivative Assets of Disposal Group, Including Discontinued Operations			45,432	52,859
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net			4,750	5,828
Disposal Group, Including Discontinued Operation, Goodwill			1,435	1,435
Assets of Disposal Group, Including Discontinued Operation, Noncurrent			631	508
Liabilities of Disposal Group, Including Discontinued Operation, Current			(129,706)	(132,951)
Derivative Liabilities of Disposal Group, Including Discontinued Operations			(30,932)	(26,084)
Liabilities of Disposal Group, Including Discontinued Operation, Noncurrent			(2,652)	(14,894)
Assets of Discontinued Operations			$ 132,431	$ 166,922

Label	Element	Value
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	$ 37,100,000
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	16,000,000
Commodity Contract [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Net Value	bkh_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetValue	$ 266,000

For the disposal group, including a component of the entity (discontinued operation), cash includes currency on hand as well as demand deposits with banks or financial institutions. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.