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Document and Entity Information Document - shares	6 Months Ended
Document and Entity Information Document - shares	Jun. 30, 2015	Jul. 31, 2015
Document Information [Line Items]
Entity Registrant Name	BLACK HILLS CORP /SD/
Entity Central Index Key	0001130464
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		44,834,944
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No

Condensed Consolidated Statements of Income (Loss) (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Revenue	$ 272,254	$ 283,237	$ 714,241	$ 743,406
Utilities -
Fuel, purchased power and cost of natural gas sold	73,824	101,331	279,151	331,799
Operations and maintenance	67,264	66,074	138,348	137,301
Non-regulated energy operations and maintenance	23,146	21,350	45,196	43,682
Depreciation, depletion and amortization	40,051	35,877	79,053	71,126
Taxes - property, production and severance	11,377	11,044	23,313	21,380
Impairment of long-lived assets	94,484	0	116,520	0
Other operating expenses	966	149	1,018	274
Total operating expenses	311,112	235,825	682,599	605,562
Operating income	(38,858)	47,412	31,642	137,844
Interest charges -
Interest expense incurred (including amortization of debt issuance costs, premiums and discounts and realized settlements on interest rate swaps)	(19,545)	(17,886)	(39,455)	(35,746)
Allowance for funds used during construction - borrowed	207	256	365	526
Capitalized interest	481	246	757	503
Interest income	301	576	749	966
Allowance for funds used during construction - equity	77	293	133	531
Other income (expense), net	395	409	726	1,000
Total other income (expense), net	(18,084)	(16,106)	(36,725)	(32,220)
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	(56,942)	31,306	(5,083)	105,624
Equity in earnings (loss) of unconsolidated subsidiaries	(47)	0	(344)	0
Impairment of equity investments	(5,170)	0	(5,170)	0
Income tax benefit (expense)	20,317	(10,959)	2,605	(36,632)
Net income (loss) available for common stock	$ (41,842)	$ 20,347	$ (7,992)	$ 68,992
Earnings (loss) per share of common stock:
Total income (loss) per share, Basic	$ (0.94)	$ 0.46	$ (0.18)	$ 1.56
Total income (loss) per share, Diluted	$ (0.94)	$ 0.46	$ (0.18)	$ 1.55
Weighted average common shares outstanding:
Basic	44,617	44,399	44,579	44,365
Diluted	44,617	44,588	44,579	44,571
Dividends declared per share of common stock	$ 0.405	$ 0.390	$ 0.810	$ 0.780

Condensed Consolidated Statement of Comprehensive Income (unaudited) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss) available for common stock	$ (41,842)	$ 20,347	$ (7,992)	$ 68,992
Other comprehensive income (loss), net of tax:
Fair value adjustments on derivatives designated as cash flow hedges (net of tax (expense) benefit of $1,171and $1,115 for the three months ended 2015 and 2014 and $128 and $2,422 for the six months ended 2015 and 2014, respectively)	(1,966)	(1,959)	(130)	(4,216)
Reclassification adjustments for cash flow hedges settled and included in net income (loss) (net of tax (expense) benefit of $735 and $(774) for the three months ended 2015 and 2014 and $1,989 and $(1,199) for the six months ended 2015 and 2014, respectively)	(1,261)	1,403	(2,502)	2,183
Benefit plan liability adjustments - net gain (loss) (net of tax (expense) benefit of $0 and $0 for the three months ended 2015 and 2014 and $15 and $2 for the six months ended 2015 and 2014, respectively)	0	0	(27)	(2)
Benefit plan liability tax adjustments - net gain (loss)	0	(394)	0	(394)
Benefit plan liability adjustments - prior service cost (net of tax (expense) benefit of $0 and $0 for the three months ended 2015 and 2014 and $0 and $(90) for the six months ended 2015 and 2014, respectively)	0	0	0	164
Reclassification adjustments of benefit plan liability - prior service cost (net of tax (expense) benefit of $19 and $39 for the three months ended 2015 and 2014 and $38 and $43 for the six months ended 2015 and 2014, respectively)	(36)	(70)	(72)	(79)
Reclassification adjustments of benefit plan liability - net gain (loss) (net of tax (expense) benefit of $(247) and $(91) for the three months ended 2015 and 2014 and $(494) and $(176) for the six months ended 2015 and 2014, respectively)	458	168	916	325
Other comprehensive income (loss), net of tax	(2,805)	(852)	(1,815)	(2,019)
Comprehensive income (loss) available for common stock	(44,647)	19,495	(9,807)	66,973
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures
Fair value adjustment on derivatives designated as cash flow hedges, (tax) benefit	1,171	1,115	128	2,422
Reclassification adjustments of cash flow hedges settled and included in net income, (tax) benefit	735	(774)	1,989	(1,199)
Benefit plan liability adjustments net gain, (tax) benefit	0	0	15	2
Benefit plan liability adjustments prior service cost, (tax) benefit	0	0	0	(90)
Reclassification adjustment of benefit plan prior service cost included in net income, (tax) benefit	19	39	38	43
Reclassification adjustment of benefit plan liabilities actuarial gain (loss), (tax) benefit	$ (247)	$ (91)	$ (494)	$ (176)

Condensed Consolidated Balance Sheets (unaudited) Statement - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Current assets:
Cash and cash equivalents	$ 87,210	$ 21,218	$ 14,697
Restricted cash and equivalents	2,316	2,056	2
Accounts receivable, net	123,661	189,992	135,145
Materials, supplies and fuel	73,749	91,191	81,164
Derivative assets, current	0	0	1,737
Income tax receivable, net	770	2,053	1,043
Deferred income tax assets, net, current	52,394	48,288	23,872
Regulatory assets, current	47,157	74,396	64,735
Other current assets	51,315	24,842	21,660
Total current assets	438,572	454,036	344,055
Investments	12,098	17,294	17,096
Property, plant and equipment	4,726,478	4,563,400	4,408,291
Less: accumulated depreciation and depletion	(1,522,969)	(1,357,929)	(1,361,233)
Total property, plant and equipment, net	3,203,509	3,205,471	3,047,058
Other assets:
Goodwill	353,396	353,396	353,396
Intangible assets, net	3,211	3,176	3,286
Regulatory assets, non-current	180,815	183,443	138,226
Other assets, non-current	28,670	29,086	31,808
Total other assets, non-current	566,092	569,101	526,716
TOTAL ASSETS	4,220,271	4,245,902	3,934,925
Current liabilities:
Accounts payable	78,021	124,139	100,098
Accrued liabilities	160,528	170,115	141,177
Derivative liabilities, current	3,289	3,340	3,480
Regulatory liabilities, current	10,910	3,687	828
Notes payable	105,760	75,000	132,700
Current maturities of long-term debt	0	275,000	275,000
Total current liabilities	358,508	651,281	653,283
Long-term debt, net of current maturities	1,567,727	1,267,589	1,121,950
Deferred credits and other liabilities:
Deferred income tax liabilities, net, non-current	510,435	511,952	463,680
Derivative liabilities, non-current	1,433	2,680	4,251
Regulatory liabilities, non-current	150,835	145,144	119,462
Benefit plan liabilities	165,791	158,966	116,403
Other deferred credits and other liabilities	154,656	154,406	137,765
Total deferred credits and other liabilities	983,150	973,148	841,561
Commitments and contingencies (See Notes 2, 8, 9, 14, 15)
Stockholders’ equity:
Common stock $1 par value; 100,000,000 shares authorized; issued 44,871,771; 44,714,072; and 44,682,885 shares, respectively	44,872	44,714	44,683
Additional Paid in Capital	751,679	748,840	744,505
Retained earnings	532,965	577,249	550,185
Treasury stock, at cost – 35,855; 42,226; and 40,951 shares, respectively	(1,771)	(1,875)	(1,801)
Accumulated other comprehensive income (loss)	(16,859)	(15,044)	(19,441)
Total stockholders’ equity	1,310,886	1,353,884	1,318,131
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 4,220,271	$ 4,245,902	$ 3,934,925

Condensed Consolidated Balance Sheets (unaudited) Condensed Consolidated Balance Sheets (Parentheticals) - $ / shares	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Statement of Financial Position [Abstract]
Common Stock, Par Per Share	$ 1	$ 1	$ 1
Common Stock, Shares Issued	44,871,771	44,714,072	44,682,885
Treasury Stock, Shares	35,855	42,226	40,951
Common Stock, Shares Authorized	100,000,000	100,000,000	100,000,000

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities:
Net income (loss) available for common stock	$ (7,992)	$ 68,992
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	79,053	71,126
Deferred financing cost amortization	1,119	1,107
Impairment of long-lived assets	121,690	0
Derivative fair value adjustments	(5,249)	(1,660)
Stock compensation	3,098	6,908
Deferred income taxes	(6,277)	36,129
Employee benefit plans	10,467	7,409
Other adjustments, net	3,720	1,481
Changes in certain operating assets and liabilities:
Materials, supplies and fuel	20,218	7,314
Accounts receivable, unbilled revenues and other operating assets	63,172	47,598
Accounts payable and other operating liabilities	(66,294)	(24,978)
Regulatory assets - current	27,178	(43,604)
Regulatory liabilities - current	7,290	(9,845)
Other operating activities, net	3,215	5,858
Net cash provided by (used in) operating activities	254,408	173,835
Investing activities:
Property, plant and equipment additions	(206,472)	(177,302)
Other investing activities	(652)	(2,994)
Net Cash Provided by (Used in) Investing Activities	(207,124)	(180,296)
Financing activities:
Dividends paid on common stock	(36,292)	(34,803)
Common stock issued	1,702	1,693
Short-term borrowings - issuances	154,460	214,100
Short-term borrowings - repayments	(123,700)	(163,900)
Long-term debt - issuances	300,000	0
Long-term debt - repayments	(275,000)	0
Other financing activities	(2,462)	(3,773)
Net cash provided by (used in) financing activities	18,708	13,317
Net change in cash and cash equivalents	65,992	6,856
Cash and Cash Equivalents
Cash and cash equivalents, beginning of period	21,218	7,841
Cash and cash equivalents, end of period	$ 87,210	$ 14,697

Management's Statement:

6 Months Ended

Jun. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [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 2014 Annual Report on Form 10-K/A filed with the SEC.

We conduct our operations through the following reportable segments: Electric Utilities, Gas Utilities, Power Generation, Coal Mining and Oil and Gas. 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.

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 June 30, 2015, December 31, 2014, and June 30, 2014 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 electric utilities is June through August while the normal peak usage season for gas utilities is November through March. 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 and six months ended June 30, 2015 and June 30, 2014, and our financial condition as of June 30, 2015, December 31, 2014, and June 30, 2014, 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.

Recently Issued and Adopted Accounting Standards

We have implemented all new accounting pronouncements that are in effect and may impact our financial statements. We are currently assessing the impact any other new accounting pronouncements that have been issued may have on our financial position, results of operations, or cash flows.

Simplifying the Presentation of Debt Issuance Costs, ASU 2015-03

In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs. Debt issuance costs related to a recognized debt liability will be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts, rather than as an asset. Amortization of these costs will continue to be reported as interest expense. ASU 2015-03 is effective for annual and interim reporting periods beginning after December 15, 2015. Early adoption is permitted. We are currently evaluating the impact of adoption that ASU 2015-03 will have on our financial position, results of operations, or cash flows.

Revenue from Contracts with Customers, ASU 2014-09

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The core principle of the model is to recognize revenue when control of the goods or services transfers to the customer, as opposed to recognizing revenue when the risks and rewards transfer to the customer under the existing revenue guidance. On July 9, 2015, FASB voted to defer the effective date of ASU 2014-09 by one year. The guidance would be effective for annual and interim reporting periods beginning after December 15, 2018 and early adoption is permitted. We are currently assessing the impact that adoption of ASU 2014-09 will have on our financial position, results of operations or cash flows.

Correction of Immaterial Errors

In preparing our condensed consolidated financial statements for the quarter ended June 30, 2015, we identified immaterial errors that impacted our previously issued consolidated financial statements. The prior period errors originated in the year ended December 31, 2008 and related to our oil and gas full cost ceiling impairment calculation to determine whether the net book value of the our oil and gas properties exceeded the ceiling. Specifically, the errors related to evaluating and correctly accounting for the treatment of tax related amounts associated with the calculation. The errors identified caused an understatement of 2008, 2009, 2012 and Q1 2015 noncash ceiling test impairment calculations, which resulted in an overstatement of depletion expense from 2009 through March 31, 2015, and an understatement of the 2012 gain on sale of oil and gas properties.

In accordance with Staff Accounting Bulletin (SAB) No. 99, Materiality, and SAB No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements, we evaluated these errors, including both qualitative and quantitative considerations, and concluded that the errors did not, individually or in the aggregate, result in a material misstatement of our previously issued condensed consolidated financial statements.

The following tables present the revisions to particular line items resulting from the corrections of these errors in this Quarterly Report on Form 10-Q. The impact of the errors relate entirely to our Oil and Gas segment.

CONDENSED CONSOLIDATED STATEMENTS OF INCOME



	For the Three Months Ended June 30, 2014									For the Six Months Ended June 30, 2014
	As Reported			Adjustments			As Revised			As Reported			Adjustments			As Revised
	(in thousands expect per share amounts)

Depreciation, depletion and amortization	$	36,712		$	(835	)	$	35,877		$	72,795		$	(1,669	)	$	71,126
Total operating expenses	$	236,660		$	(835	)	$	235,825		$	607,231		$	(1,669	)	$	605,562

Operating income (loss)	$	46,577		$	835		$	47,412		$	136,175		$	1,669		$	137,844

Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	$	30,471		$	835		$	31,306		$	103,955		$	1,669		$	105,624
Income tax benefit (expense)	$	(10,651	)	$	(308	)	$	(10,959	)	$	(36,017	)	$	(615	)	$	(36,632	)
Net income (loss) available for common stock	$	19,820		$	527		$	20,347		$	67,938		$	1,054		$	68,992

Earnings (loss) per share of common stock:
Earnings (loss) per share, Basic	$	0.45		$	0.01		$	0.46		$	1.53		$	0.03		$	1.56
Earnings (loss) per share, Diluted	$	0.44		$	0.02		$	0.46		$	1.52		$	0.03		$	1.55

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)



	For the Three Months Ended June 30, 2014						For the Six Months Ended June 30, 2014
(in thousands)	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income (loss) available for common stock	$	19,820	$	527	$	20,347	$	67,938	$	1,054	$	68,992
Comprehensive income (loss)	$	18,968	$	527	$	19,495	$	65,919	$	1,054	$	66,973

CONDENSED CONSOLIDATED BALANCE SHEET



	As of June 30, 2014
	As Reported			Adjustments			As Revised
	(in thousands)
Accumulated depreciation and depletion	$	(1,325,660	)	$	(35,573	)	$	(1,361,233	)
Total property, plant and equipment, net	$	3,082,631		$	(35,573	)	$	3,047,058
TOTAL ASSETS	$	3,970,498		$	(35,573	)	$	3,934,925

Deferred income tax liability, non-current	$	476,059		$	(12,379	)	$	463,680
Total deferred credits and other liabilities	$	853,940		$	(12,379	)	$	841,561

Retained earnings	$	573,379		$	(23,194	)	$	550,185
Total stockholders' equity	$	1,341,325		$	(23,194	)	$	1,318,131
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$	3,970,498		$	(35,573	)	$	3,934,925

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS



	Six Months Ended June 30, 2014
	As Reported		Adjustments			As Revised
	(in thousands)
Net income (loss) available for common stock	$	67,938	$	1,054		$	68,992

Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	$	72,795	$	(1,669	)	$	71,126
Deferred income taxes	$	35,514	$	615		$	36,129
Net cash provided by (used in) operating activities	$	173,835	$	—		$	173,835

The Notes to the Condensed Consolidated Financial Statements have been revised to reflect the correction of these errors for all periods presented.

Subsequent Event:	6 Months Ended
Subsequent Event:	Jun. 30, 2015
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENT Acquisition of SourceGas On July 12, 2015, Black Hills Utility Holdings entered in a definitive agreement to acquire SourceGas Holdings LLC and its subsidiaries from investment funds managed by Alinda Capital Partners and GE Energy Financial Services, a unit of General Electric Co. (NYSE:GE), for approximately $1.89 billion, which includes $200 million of projected capital expenditures through closing and the assumption of $720 million in debt projected at closing. The effective purchase price is estimated to be $1.74 billion after taking into account approximately $150 million of tax benefits consisting of acquired NOLs and goodwill tax benefits resulting from the transaction. The purchase price is subject to customary post-closing adjustments for cash, capital expenditures, indebtedness and working capital. In conjunction with the agreement, we have entered into a commitment letter for a one-year, $1.17 billion senior unsecured fully committed bridge facility to be provided by Credit Suisse. We expect to finance the acquisition with the aforementioned $720 million of assumed debt, $450 million to $550 million of new debt, $575 million to $675 million of equity and equity-linked securities, and the remainder with cash on hand and Revolver draws. SourceGas primarily operates four regulated natural gas utilities serving approximately 425,000 customers in Arkansas, Colorado, Nebraska and Wyoming and a 512 mile regulated intrastate natural gas transmission pipeline in Colorado. Following completion of the transaction, SourceGas will be a wholly-owned subsidiary of Black Hills Utility Holdings. The agreement for the acquisition of SourceGas is subject to various provisions including representations, warranties, and covenants with respect to Arkansas, Colorado, Nebraska and Wyoming utility businesses that are subject to customary conditions and limitations. Completion of the transaction is also subject to regulatory approvals from the APSC, CPUC, NPSC and WPSC, and is also subject to notification, clearance and reporting requirements under the Hart-Scott-Rodino Act. The acquisition is expected to close during the first half of 2016. BHC has guaranteed the full and complete payment and performance of Black Hills Utility Holdings. Effective August 6^th, 2015, we entered into a Bridge Term Loan Agreement with Credit Suisse as the Administrate Agent and 10 additional banks, collectively, for commitments totaling $1.17 billion billion pursuant to the previously executed bridge commitment letter with Credit Suisse. We may draw up to $1.17 billion billion on this loan to fund the SourceGas Acquisition and related expenses. The Agreement contains the same customary affirmative and negative covenants as are in our Revolving Credit Agreement and Term Loan Agreement, such as limitations on the creation of new indebtedness and on certain liens, restrictions on certain transactions and maintaining a recourse leverage ratio not to exceed 0.75 to 1 . In the event we fund under the Bridge Term Loan Agreement, in certain circumstances, we are required to pay down those borrowings with funds received from the proceeds of equity and debt offerings and asset sales. Additionally, our Revolving Credit Facility and Term Loan Credit Agreements were amended in connection with the Bridge Loan Credit Agreement to permit the assumption of certain indebtedness of SourceGas and to increase the Recourse Leverage Ratio in certain circumstances. In these amendments, the maximum Recourse Ratio is no greater than 0.65 to 1 at the end of any fiscal quarter, but may increase to (i) 0.70 to 1 at the end of any fiscal quarter during such four fiscal quarter period where the aggregate outstanding debt assumed or incurred in connection with our acquisition of SourceGas is equal to or greater than $1.25 billion billion and less than $1.46 billion billion or (ii) 0.75 to 1 at the end of any fiscal quarter during such four fiscal quarter period that the aggregate outstanding debt assumed or incurred in connection with our acquisition of SourceGas is equal to or greater than $1.46 billion.

Business Segment Information:

6 Months Ended

Jun. 30, 2015

Segment Reporting Information, Additional Information [Abstract]

Business Segment Information

BUSINESS SEGMENT INFORMATION

Segment information and Corporate activities included in the accompanying Condensed Consolidated Statements of Income (Loss) were as follows (in thousands):



Three Months Ended June 30, 2015	External Operating Revenue		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	169,751	$	2,509		$	17,702
Gas	79,426		—			3,165
Non-regulated Energy:
Power Generation	1,706		20,603			7,549
Coal Mining	9,052		7,673			3,049
Oil and Gas ^(a)(b)	12,319		—			(71,195		)
Corporate activities^(c)	—		—			(2,112		)
Inter-company eliminations	—		(30,785		)	—
Total	$	272,254	$	—		$	(41,842	)



Three Months Ended June 30, 2014	External Operating Revenue		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	158,740	$	3,144		$	11,427
Gas	102,499		—			1,994
Non-regulated Energy:
Power Generation	1,267		20,713			7,194
Coal Mining	5,583		9,068			2,016
Oil and Gas	15,148		—			(1,133		)
Corporate activities	—		—			(1,151		)
Inter-company eliminations	—		(32,925		)	—
Total	$	283,237	$	—		$	20,347




Six Months Ended June 30, 2015	External Operating Revenues		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	352,725	$	5,933		$	36,631
Gas	317,077		—			25,377
Non-regulated Energy:
Power Generation	3,659		41,324			15,694
Coal Mining	17,194		15,465			6,059
Oil and Gas ^(a)(b)	23,586		—			(90,310		)
Corporate activities ^(c)	—		—			(1,443		)
Inter-company eliminations	—		(62,722		)	—
Total	$	714,241	$	—		$	(7,992	)




Six Months Ended June 30, 2014	External Operating Revenues		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	336,835	$	7,151		$	26,002
Gas	361,836		—			26,692
Non-regulated Energy:
Power Generation	2,536		41,792			15,267
Coal Mining	12,201		17,948			4,480
Oil and Gas	29,998		—			(2,628		)
Corporate activities	—		—			(821		)
Inter-company eliminations	—		(66,891		)	—
Total	$	743,406	$	—		$	68,992

__________


(a)	Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.


(b)	Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.

(c) Net income (loss) for the three and six months ended June 30, 2015 included acquisition costs, net of tax of $0.5 million and $0.3 million, respectively. See Note 2 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.

Segment information and Corporate balances included in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands):



Total Assets (net of inter-company eliminations) as of:	June 30, 2015		December 31, 2014		June 30, 2014
Utilities:
Electric ^(a)	$	2,856,903	$	2,748,680	$	2,603,900
Gas	801,295		906,922		799,365
Non-regulated Energy:
Power Generation^(a)	72,270		76,945		85,269
Coal Mining	76,079		74,407		73,701
Oil and Gas ^{(b) (c)}	275,068		332,343		272,264
Corporate activities	138,656		106,605		100,426
Total assets	$	4,220,271	$	4,245,902	$	3,934,925

__________


(a)	The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease.


(b)	As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.


(c)	Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015.

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Paragraph 33
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

+ Details

Accounts Receivable:

6 Months Ended

Jun. 30, 2015

Receivables [Abstract]

Accounts Receivable

ACCOUNTS RECEIVABLE

Following is a summary of Accounts receivable, net included in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	Accounts		Unbilled		Less Allowance for			Accounts
June 30, 2015	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	46,381	$	33,501	$	(685	)	$	79,197
Gas Utilities	25,635		9,418		(1,259		)	33,794
Power Generation	1,199		—		—			1,199
Coal Mining	3,402		—		—			3,402
Oil and Gas	5,099		—		(13		)	5,086
Corporate	983		—		—			983
Total	$	82,699	$	42,919	$	(1,957	)	$	123,661



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2014	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	59,714	$	26,474	$	(722	)	$	85,466
Gas Utilities	47,394		45,546		(781		)	92,159
Power Generation	1,369		—		—			1,369
Coal Mining	3,151		—		—			3,151
Oil and Gas	5,305		—		(13		)	5,292
Corporate	2,555		—		—			2,555
Total	$	119,488	$	72,020	$	(1,516	)	$	189,992



	Accounts		Unbilled		Less Allowance for			Accounts
June 30, 2014	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	48,333	$	21,716	$	(622	)	$	69,427
Gas Utilities	43,104		9,265		(1,027		)	51,342
Power Generation	1,388		—		—			1,388
Coal Mining	1,866		—		—			1,866
Oil and Gas	9,123		—		(13		)	9,110
Corporate	2,012		—		—			2,012
Total	$	105,826	$	30,981	$	(1,662	)	$	135,145

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Regulatory Accounting:

6 Months Ended

Jun. 30, 2015

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Accounting

REGULATORY ACCOUNTING

We had the following regulatory assets and liabilities (in thousands):



	Maximum	As of		As of		As of
	Amortization (in years)	June 30, 2015		December 31, 2014		June 30, 2014
Regulatory assets
Deferred energy and fuel cost adjustments - current^{(a) (d)}	1	$	26,862	$	23,820	$	29,605
Deferred gas cost adjustments ^(a)(d)	2	5,588		37,471		35,479
Gas price derivatives ^(a)	7	17,907		18,740		3,561
AFUDC^(b)	45	12,321		12,358		12,468
Employee benefit plans ^{(c) (e)}	12	96,734		97,126		65,874
Environmental^(a)	subject to approval	1,224		1,314		1,314
Asset retirement obligations^(a)	44	3,242		3,287		3,278
Bond issue cost^(a)	23	3,204		3,276		3,347
Renewable energy standard adjustment ^(a)	5	5,629		9,622		14,501
Flow through accounting^(c)	35	27,861		25,887		22,754
Decommissioning costs ^(f)	10	14,845		12,484		—
Other regulatory assets^(a)	15	12,555		12,454		10,780
		$	227,972	$	257,839	$	202,961

Regulatory liabilities
Deferred energy and gas costs^{(a) (d)}	1	$	16,114	$	6,496	$	6,490
Employee benefit plans^{(c) (e)}	12	53,163		53,139		34,356
Cost of removal^(a)	44	84,118		78,249		70,841
Other regulatory liabilities^(c)	25	8,350		10,947		8,603
		$	161,745	$	148,831	$	120,290

__________


(a)	Recovery of costs, but we are not allowed a rate of return.


(b)	In addition to recovery of costs, we are allowed a rate of return.


(c)	In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively.

(d)

Our deferred energy, fuel cost, and gas cost adjustments represent the cost of electricity and gas delivered to our electric and gas utility customers that is either higher or lower than current rates and will be recovered or refunded in future rates. Fluctuations in deferred gas cost adjustments compared to the same period in the prior year are primarily due to higher natural gas prices driven by demand and market conditions from the peak winter heating season in the first part of 2014. Our electric and gas utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state utility commissions.


(e)	Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.


(f)	Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

Materials, Supplies and Fuel:

6 Months Ended

Jun. 30, 2015

Inventory, Net [Abstract]

Materials, Supplies and Fuel

MATERIALS, SUPPLIES AND FUEL

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



	June 30, 2015		December 31, 2014		June 30, 2014
Materials and supplies	$	54,646	$	49,555	$	51,925
Fuel - Electric Utilities	6,644		6,637		7,679
Natural gas in storage held for distribution	12,459		34,999		21,560
Total materials, supplies and fuel	$	73,749	$	91,191	$	81,164

Earnings Per Share:

6 Months Ended

Jun. 30, 2015

Earnings Per Share [Abstract]

Earnings Per Share

EARNINGS PER SHARE

A reconciliation of share amounts used to compute Earnings (loss) per share in the accompanying Condensed Consolidated Statements of Income (loss) was as follows (in thousands):



	Three Months Ended June 30,					Six Months Ended June 30,
	2015			2014		2015			2014

Net income (loss) available for common stock	$	(41,842	)	$	20,347	$	(7,992	)	$	68,992

Weighted average shares - basic	44,617			44,399		44,579			44,365
Dilutive effect of:
Equity compensation	—			189		—			206
Weighted average shares - diluted	44,617			44,588		44,579			44,571

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

Due to our net loss the for the three and six months ended June 30, 2015, potentially dilutive securities were excluded from the diluted loss per share calculation due to their anti-dilutive effect. In computing diluted net loss per share, 83,613 and 101,146 equity compensation shares were excluded from the computations for the three and six months ended June 30, 2015, respectively.

In addition to these potentially dilutive shares excluded due to our net loss for the three and six months ended June 30, 2015, the following outstanding securities were also excluded in the computation of diluted net income (loss) per share as their inclusion would have been anti-dilutive (in thousands):



	Three Months Ended June 30,		Six Months Ended June 30,
	2015	2014	2015	2014

Equity compensation	119	81	113	63
Anti-dilutive shares	119	81	113	63

Notes Payable and Long-term Debt:

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Notes Payable and Long-term debt

NOTES PAYABLE AND LONG-TERM DEBT

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



	June 30, 2015				December 31, 2014				June 30, 2014
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	105,760	$	23,100	$	75,000	$	35,000	$	132,700	$	20,272

Revolving Credit Facility

On June 26, 2015, we amended our $500 million corporate Revolving Credit Facility agreement to extend the term through June 26, 2020. This facility is similar to the former agreement, which includes an accordion feature that allows us, with the consent of the administrative agent and issuing agents, to increase the capacity of the facility to $750 million. Borrowings continue to be available under a base rate or various Eurodollar rate options. The interest costs associated with the letters of credit or borrowings and the commitment fee under the Revolving Credit Facility are determined based upon our most favorable Corporate credit rating from S&P and Moody’s for our unsecured debt. Based on our credit ratings, the margins for base rate borrowings, Eurodollar borrowings, and letters of credit were 0.125%, 1.125%, and 1.125%, respectively at June 30, 2015. A commitment fee is charged on the unused amount of the Revolving Credit Facility and was 0.175% based on our credit rating.

Replacement of Corporate Term Loan

On April 13, 2015, we entered into a new $300 million Corporate term loan expiring April 12, 2017. This new term loan replaced the $275 million Corporate term loan due on June 19, 2015 and was classified as Long-Term Debt as of June 30, 2015. The additional $25 million, less interest and fees, was used for general corporate purposes. The cost of the borrowing under the new term loan is LIBOR plus a margin of 0.9%. The covenants on the new term loan are substantially the same as the Revolving Credit Facility.

Debt Covenants

Our Revolving Credit Facility and our Term Loan require compliance with the following financial covenant at the end of each quarter:



	As of June 30, 2015	Covenant Requirement
Recourse Leverage Ratio	57%	Less than	65%

As of June 30, 2015, we were in compliance with this covenant.

Risk Management Activities:

6 Months Ended

Jun. 30, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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 2014 Annual Report on Form 10-K/A.

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 including, but not limited to:


•	Commodity price risk associated with our natural long position in crude oil and natural gas reserves and production; and our fuel procurement for certain of our gas-fired generation assets; and


•	Interest rate risk associated with our variable-rate debt.

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 high credit quality entities, 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.

Our derivative and hedging activities recorded in the accompanying Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Income (Loss) and Condensed Consolidated Statements of Comprehensive Income (Loss) are detailed below and in Note 10.

Oil and Gas

We produce natural gas, NGLs 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.

To mitigate commodity price risk and preserve cash flows, we primarily use exchange traded futures and related options to hedge portions of our crude oil and natural gas production. We elect hedge accounting on these instruments. These transactions were designated at inception as cash flow hedges, documented under accounting standards 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 were recorded as Derivative assets or Derivative liabilities on the accompanying Condensed Consolidated Balance Sheets, net of balance sheet offsetting as permitted by GAAP. The effective portion of the gain or loss on these derivatives for which we have elected cash flow hedge accounting is reported in AOCI in the accompanying Condensed Consolidated Balance Sheets and the ineffective portion, if any, is reported in Revenue in the accompanying Condensed Consolidated Statements of Income (Loss).

The contract or notional amounts, terms of our commodity derivatives, and the derivative balances for our Oil and Gas segment reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of:



	June 30, 2015				December 31, 2014				June 30, 2014
	Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps		Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps		Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps
Notional ^(a)	276,000		4,187,500		334,500		6,582,500		424,500		9,265,000
Maximum terms in months ^(b)	1		1		1		1		1		1
Derivative assets, current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative assets, non-current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative liabilities, current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative liabilities, non-current	$	—	$	—	$	—	$	—	$	—	$	—

__________


(a)	Crude oil in Bbls, natural gas in MMBtus.


(b)	Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument.

Based on June 30, 2015 prices, a $6.4 million gain would be reclassified from AOCI over the next 12 months. Estimated and actual realized gains or losses will change during future periods as market prices fluctuate.

Utilities

The operations of our utilities, including natural gas sold by our Gas Utilities and natural gas used for Electric Utility generation plants or those plants under PPAs where our Electric Utilities must provide the generation fuel (tolling agreements), expose our utility customers to volatility in natural gas prices. Therefore, as allowed or required by state utility commissions, we have entered into commission approved hedging programs utilizing 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, net of balance sheet offsetting as permitted by GAAP. Unrealized and realized gains and losses, as well as option premiums and commissions on these transactions are recorded as Regulatory assets or Regulatory liabilities in the accompanying Condensed Consolidated Balance Sheets in accordance with state commission guidelines. When the related costs are recovered through our rates, the hedging activity is recognized in the Condensed Consolidated Statements of Income (Loss), or the Condensed Consolidated Statements of Comprehensive Income (Loss).

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



	June 30, 2015		December 31, 2014		June 30, 2014
	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)
Natural gas futures purchased	17,270,000	66	19,370,000	72	16,240,000	78
Natural gas options purchased	3,980,000	9	4,020,000	8	3,980,000	9
Natural gas basis swaps purchased	14,445,000	54	12,005,000	60	13,415,000	66

__________

(a) Term reflects the maximum forward period hedged.

We had the following derivative balances related to the hedges in our Utilities reflected in our Condensed Consolidated Balance Sheets as of (in thousands):



	June 30, 2015		December 31, 2014		June 30, 2014
Derivative assets, current	$	—	$	—	$	1,737
Derivative assets, non-current	$	—	$	—	$	—
Derivative liabilities, non-current	$	—	$	—	$	—
Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities	$	17,907	$	18,740	$	3,561

Financing Activities

We entered into floating-to-fixed interest rate swap agreements to reduce our exposure to interest rate fluctuations associated with our floating rate debt obligations. The contract or notional amounts, terms of our interest rate swaps and the interest rate swaps balances reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of:



	June 30, 2015			December 31, 2014			June 30, 2014
	Interest Rate Swaps^(a)			Interest Rate Swaps^(a)			Interest Rate Swaps^(a)
Notional	$	75,000		$	75,000		$	75,000
Weighted average fixed interest rate	4.97		%	4.97		%	4.97		%
Maximum terms in years	1.50			2.00			2.50
Derivative liabilities, current	$	3,289		$	3,340		$	3,480
Derivative liabilities, non-current	$	1,433		$	2,680		$	4,251

__________


(a)	These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings.

Based on June 30, 2015 market interest rates and balances related to our interest rate swaps, a loss of approximately $3.3 million would be realized, reported in pre-tax earnings and reclassified from AOCI during the next 12 months. Estimated and actual realized gains or losses will change during future periods as market interest rates change.

Cash Flow Hedges

The impacts of cash flow hedges on our Condensed Consolidated Statements of Income (Loss) were as follows (in thousands):



Three Months Ended June 30, 2015
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	$	(892	)	Interest expense	$	(1,670	)		$	—
Commodity derivatives	(2,245		)	Revenue	3,666				—
Total	$	(3,137	)		$	1,996			$	—



Three Months Ended June 30, 2014
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	$	(337	)	Interest expense	$	(926	)		$	—
Commodity derivatives	(2,737		)	Revenue	(1,251		)		—
Total	$	(3,074	)		$	(2,177	)		$	—




Six Months Ended June 30, 2015
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	$	(1,778	)	Interest expense	$	(3,107	)		$	—
Commodity derivatives	1,520			Revenue	7,598				—
Total	$	(258	)		$	4,491			$	—




Six Months Ended June 30, 2014
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	$	(429	)	Interest expense	$	(1,820	)		$	—
Commodity derivatives	(6,209		)	Revenue	(1,562		)		—
Total	$	(6,638	)		$	(3,382	)		$	—

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
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+ Details

Fair Value Measurements:

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Derivative Financial Instruments

The accounting guidance for fair value measurements requires certain disclosures about assets and liabilities measured at fair value. This guidance establishes a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value. 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. For additional information see Notes 1, 8, 9 and 10 to the Consolidated Financial Statements included in our 2014 Annual Report on Form 10-K/A filed with the SEC.

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

Valuation Methodologies for Derivatives

Oil and Gas Segment:


•	The commodity contracts for our Oil and Gas segment are valued using the market approach and include exchange-traded futures and basis swaps. Fair value was derived using exchange quoted settlement prices from third party brokers for similar instruments as to quantity and timing. The prices are then validated through third-party sources and therefore support Level 2 disclosure.

Utilities Segments:


•	The commodity contracts for our Utilities Segments, valued using the market approach, include exchange-traded futures, options and basis swaps (Level 2) for natural gas contracts. For Level 2 assets and liabilities, fair value was derived using broker quotes validated by the exchange settlement pricing for the applicable contract.

Corporate Activities:

•

The interest rate swaps are valued using the market approach. We establish 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 a 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

There have been no significant transfers between Level 1 and Level 2 derivative balances. Amounts included in cash collateral and counterparty netting in the following tables represent the impact of legally enforceable master netting agreements that allow us to settle positive and negative positions, netting of asset and liability positions permitted in accordance with accounting standards for offsetting as well as cash collateral posted with the same counterparties.

The following tables set forth by level within the fair value hierarchy our gross assets and gross liabilities and related offsetting as permitted by GAAP that were accounted for at fair value on a recurring basis for derivative instruments. A discussion of fair value of financial instruments is included in Note 11:



	As of June 30, 2015
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		5,178		—		(5,178		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		4,372		—		(4,372		)	—
Commodity derivatives — Utilities	—		2,577		—		(2,577		)	—
Total	$	—	$	12,127	$	—	$	(12,127	)	$	—

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		112		—		(112		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		498		—		(498		)	—
Commodity derivatives — Utilities	—		18,758		—		(18,758		)	—
Interest rate swaps	—		4,722		—		—			4,722
Total	$	—	$	24,090	$	—	$	(19,368	)	$	4,722



	As of December 31, 2014
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		8,599		—		(8,599		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		6,558		—		(6,558		)	—
Commodity derivatives —Utilities	—		2,389		—		(2,389		)	—
Total	$	—	$	17,546	$	—	$	(17,546	)	$	—

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		—		—		—			—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		473		—		(473		)	—
Commodity derivatives — Utilities	—		19,303		—		(19,303		)	—
Interest rate swaps	—		6,020		—		—			6,020
Total	$	—	$	25,796	$	—	$	(19,776	)	$	6,020



	As of June 30, 2014
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		—		—		—			—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		600		—		(600		)	—
Commodity derivatives — Utilities	—		4,342		—		(2,605		)	1,737
Total	$	—	$	4,942	$	—	$	(3,205	)	$	1,737

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		4,020		—		(4,020		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		2,030		—		(2,030		)	—
Commodity derivatives — Utilities	—		5,989		—		(5,989		)	—
Interest rate swaps	—		7,731		—		—			7,731
Total	$	—	$	19,770	$	—	$	(12,039	)	$	7,731

Fair Value Measures by Balance Sheet Classification

As required by accounting standards for derivatives and hedges, fair values within the following tables are presented on a gross basis aside from the netting of asset and liability positions permitted in accordance with accounting standards for offsetting and under terms of our master netting agreements and the impact of legally enforceable master netting agreements that allow us to settle positive and negative positions. However, the amounts do not include net cash collateral on deposit in margin accounts at June 30, 2015, December 31, 2014, and June 30, 2014, to collateralize certain financial instruments, which are included in Derivative assets and/or Derivative liabilities. Therefore, the 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 9.

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



As of June 30, 2015
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	6,931	$	—
Commodity derivatives	Derivative assets — non-current	2,619		—
Commodity derivatives	Derivative liabilities — current	—		493
Commodity derivatives	Derivative liabilities — non-current	—		117
Interest rate swaps	Derivative liabilities — current	—		3,289
Interest rate swaps	Derivative liabilities — non-current	—		1,433
Total derivatives designated as hedges		$	9,550	$	5,332

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		5,156
Commodity derivatives	Derivative liabilities — non-current	—		11,025
Total derivatives not designated as hedges		$	—	$	16,181



As of December 31, 2014
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	10,391	$	—
Commodity derivatives	Derivative assets — non-current	4,766		—
Commodity derivatives	Derivative liabilities — current	—		185
Commodity derivatives	Derivative liabilities — non-current	—		288
Interest rate swaps	Derivative liabilities — current	—		3,340
Interest rate swaps	Derivative liabilities — non-current	—		2,680
Total derivatives designated as hedges		$	15,157	$	6,493

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		8,032
Commodity derivatives	Derivative liabilities — non-current	—		8,882
Total derivatives not designated as hedges		$	—	$	16,914



As of June 30, 2014
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	262	$	—
Commodity derivatives	Derivative assets — non-current	338		—
Commodity derivatives	Derivative liabilities — current	—		3,702
Commodity derivatives	Derivative liabilities — non-current	—		2,348
Interest rate swaps	Derivative liabilities — current	—		3,480
Interest rate swaps	Derivative liabilities — non-current	—		4,251
Total derivatives designated as hedges		$	600	$	13,781

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	1,737	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		3,384
Total derivatives not designated as hedges		$	1,737	$	3,384

Fair Value of Financial Instruments:

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

FAIR VALUE OF FINANCIAL INSTRUMENTS

The estimated fair values of our financial instruments, excluding derivatives which are presented in Note 10, were as follows (in thousands) as of:



	June 30, 2015				December 31, 2014				June 30, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Cash and cash equivalents ^(a)	$	87,210	$	87,210	$	21,218	$	21,218	$	14,697	$	14,697
Restricted cash and equivalents ^(a)	$	2,316	$	2,316	$	2,056	$	2,056	$	2	$	2
Notes payable ^(a)	$	105,760	$	105,760	$	75,000	$	75,000	$	132,700	$	132,700
Long-term debt, including current maturities ^(b)	$	1,567,727	$	1,700,487	$	1,542,589	$	1,734,555	$	1,396,950	$	1,578,756

__________


(a)	Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy.


(b)	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.

- Definition

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.

+ References + Details

Other Comprehensive Income (Loss):

6 Months Ended

Jun. 30, 2015

Statement of Comprehensive Income [Abstract]

Other Comprehensive Income (Loss)

OTHER COMPREHENSIVE INCOME (LOSS)

The components of the reclassification adjustments, net of tax, included in Other Comprehensive Income (Loss) for the periods were as follows (in thousands):



	Location on the Condensed Consolidated Statements of Income (Loss)	Amount Reclassified from AOCI
		Three Months Ended						Six Months Ended
		June 30, 2015			June 30, 2014			June 30, 2015			June 30, 2014
Gains (losses) on cash flow hedges:
Interest rate swaps	Interest expense	$	1,670		$	926		$	3,107		$	1,820
Commodity contracts	Revenue	(3,666		)	1,251			(7,598		)	1,562
		(1,996		)	2,177			(4,491		)	3,382
Income tax	Income tax benefit (expense)	735			(774		)	1,989			(1,199		)
Reclassification adjustments related to cash flow hedges, net of tax		$	(1,261	)	$	1,403		$	(2,502	)	$	2,183

Amortization of defined benefit plans:
Prior service cost	Utilities - Operations and maintenance	$	(26	)	$	(25	)	$	(53	)	$	(51	)
	Non-regulated energy operations and maintenance	(29		)	(84		)	(57		)	(71		)

Actuarial gain (loss)	Utilities - Operations and maintenance	454			158			908			315
	Non-regulated energy operations and maintenance	251			101			502			186
		650			150			1,300			379
Income tax	Income tax benefit (expense)	(228		)	(52		)	(456		)	(133		)
Reclassification adjustments related to defined benefit plans, net of tax		$	422		$	98		$	844		$	246

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, 2013	$	(7,133	)	$	(10,289	)	$	(17,422	)
Other comprehensive income (loss), net of tax	(1,478		)	311			(1,167		)
Balance as of March 31, 2014	(8,611		)	(9,978		)	(18,589		)
Other comprehensive income (loss), net of tax	(556		)	(296		)	(852		)
Balance as of June 30, 2014	$	(9,167	)	$	(10,274	)	$	(19,441	)

Balance as of December 31, 2014	$	5,093		$	(20,137	)	$	(15,044	)
Other comprehensive income (loss), net of tax	595			395			990
Balance as of March 31, 2015	5,688			(19,742		)	(14,054		)
Other comprehensive income (loss), net of tax	422			(3,227		)	(2,805		)
Balance as of June 30, 2015	$	6,110		$	(22,969	)	$	(16,859	)

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e689-108580

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-Topic 220
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Supplemental Disclosure of Cash Flow Information:

6 Months Ended

Jun. 30, 2015

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION



Six months ended	June 30, 2015			June 30, 2014
	(in thousands)
Non-cash investing and financing activities from continuing operations—
Property, plant and equipment acquired with accrued liabilities	$	36,661		$	40,611
Increase (decrease) in capitalized assets associated with asset retirement obligations	$	—		$	(2,785	)

Cash (paid) refunded during the period for continuing operations—
Interest (net of amounts capitalized)	$	(37,698	)	$	(35,009	)
Income taxes, net	$	(1,202	)	$	(396	)

Employee Benefit Plans:

6 Months Ended

Jun. 30, 2015

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Employee Benefit Plans

EMPLOYEE BENEFIT PLANS

Defined Benefit Pension Plans

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Service cost	$	1,494		$	1,362		$	2,988		$	2,724
Interest cost	3,880			3,963			7,760			7,926
Expected return on plan assets	(4,867		)	(4,516		)	(9,734		)	(9,032		)
Prior service cost	15			16			30			32
Net loss (gain)	2,759			1,201			5,518			2,403
Net periodic benefit cost	$	3,281		$	2,026		$	6,562		$	4,053

Defined Benefit Postretirement Healthcare Plans

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Service cost	$	464		$	425		$	928		$	850
Interest cost	450			480			900			959
Expected return on plan assets	(33		)	(21		)	(66		)	(42		)
Prior service cost (benefit)	(107		)	(107		)	(214		)	(214		)
Net loss (gain)	102			40			204			80
Net periodic benefit cost	$	876		$	817		$	1,752		$	1,633

Supplemental Non-qualified Defined Benefit and Defined Contribution Plans

The components of net periodic benefit cost for the Supplemental Non-qualified Defined Benefit and Defined Contribution Plans were as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Service cost	$	392	$	374	$	883	$	749
Interest cost	364		362		728		724
Prior service cost	1		1		2		1
Net loss (gain)	270		124		540		249
Net periodic benefit cost	$	1,027	$	861	$	2,153	$	1,723

Contributions

We anticipate that we will make contributions to the benefit plans during 2015 and 2016. Contributions to the Defined Benefit Pension Plans are cash contributions made directly to the Pension Plan Trust accounts. Contributions to the Healthcare and Supplemental Plan are made in the form of benefit payments. Contributions and anticipated contributions are as follows (in thousands):



	Contributions Made		Contributions Made		Additional Contributions		Contributions
	Three Months Ended June 30, 2015		Six Months Ended June 30, 2015		Anticipated for 2015		Anticipated for 2016
Defined Benefit Pension Plans	$	—	$	—	$	10,200	$	10,200
Non-pension Defined Benefit Postretirement Healthcare Plans	$	939	$	1,878	$	1,877	$	4,026
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	372	$	744	$	743	$	1,544

Commitments and Contingencies:

6 Months Ended

Jun. 30, 2015

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 18 of our Notes to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K/A except for those described below and in Note 2.

Oil Creek Fire

On June 29, 2012, a forest and grassland fire occurred in the western Black Hills of Wyoming. A fire investigator retained by the Weston County Fire Protection District concluded that the fire was caused by the failure of a transmission structure owned, operated and maintained by Black Hills Power. On April 16, 2013, a large group of private landowners filed suit in the United States District Court for the District of Wyoming. There are approximately 36 Plaintiff groups (including property jointly owned by multiple family members or entities), or approximately 73 individually named private plaintiffs. In addition, the State of Wyoming has intervened in the lawsuit. Both the private landowners and the State of Wyoming assert claims for damages against Black Hills Power. The claims include allegations of negligence, negligence per se, common law nuisance and trespass. In addition to claims for compensatory damages, the lawsuit seeks recovery of punitive damages. We have denied and will vigorously defend all claims arising out of the fire. We cannot predict the outcome of expert investigation, the viability of alleged claims or the outcome of the litigation.

Civil litigation of this kind, however, is likely to lead to settlement negotiations, including negotiations prompted by pre-trial civil court procedures. We believe such negotiations would effect a settlement of all claims. Regardless of whether the litigation is determined at trial or through settlement, we expect to incur significant investigation, legal and expert services expenses associated with the litigation. We maintain insurance coverage to limit our exposure to losses due to civil liability claims, and related litigation expense, and we will pursue recoveries to the maximum extent available under the policies. The deductible applicable to some types of claims arising out of this fire is $1.0 million. Based upon information currently available, we believe that a loss associated with settlement of pending claims is probable. Accordingly, we recorded a loss contingency liability related to these claims and we recorded a receivable for costs we believe are reimbursable and probable of recovery under our insurance coverage. Both of these entries reflect our reasonable estimate of probable future litigation expense and settlement costs; we did not base these contingencies on any determination that it is probable we would be found liable for these claims were they to be litigated.

Given the uncertainty of litigation, however, a loss related to the fire, the litigation and related claims in excess of the loss we have determined to be probable is reasonably possible. We cannot reasonably estimate the amount of such possible loss because expert investigations and our review of damage claim documentation are ongoing, and there are significant factual and legal issues to be resolved. Further claims may be presented by these claimants and other parties. We have received claims seeking recovery for fire suppression, reclamation and rehabilitation costs, damage to fencing and other personal property, alleged injury to timber, grass or hay, livestock and related operations, and diminished value of real estate. Based on the legal standard for measuring damages that we believe applies to this matter, we estimate the current total claims to be approximately $55 million; however the actual amount of allowed claims and any loss will depend on the resolution of certain factual and legal issues. We are not yet able to reasonably estimate the amount of any reasonable possible losses in excess of the amount we have accrued. Based upon information currently available, however, management does not expect the outcome of the claims to have a material adverse effect upon our consolidated financial condition, results of operations or cash flows.

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 June 30, 2015, we were in compliance with the debt 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 June 30, 2015:


•	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 June 30, 2015, the restricted net assets at our Utilities Group were approximately $325 million.

Impairment of Assets:	6 Months Ended
Impairment of Assets:	Jun. 30, 2015
Asset Impairment Charges [Abstract]
Asset Impairment Charges [Text Block]	IMPAIRMENT OF ASSETS Long-lived assets Our Oil and Gas segment accounts for oil and gas activities under the full cost method of accounting. Under the full cost method, all productive and non-productive costs related to acquisition, exploration, development, abandonment and reclamation activities are capitalized. These capitalized costs, less accumulated amortization and related deferred income taxes, are subject to a ceiling test which limits the pooled costs to the aggregate of the discounted value of future net revenue attributable to proved natural gas and crude oil reserves using a discount rate defined by the SEC plus the lower of cost or market value of unevaluated properties. Any costs in excess of the ceiling are written off as a non-cash charge. During the first quarter of 2015, we recorded a $22 million pre-tax non-cash impairment of oil and gas assets included in our Oil and Gas segment. In determining the ceiling value of our assets under the full cost accounting rules of the SEC, we utilized the average of the quoted prices from the first day of each month from the previous 12 months. For natural gas, the average NYMEX price was $3.88 per Mcf, adjusted to $2.69 per Mcf at the wellhead; for crude oil, the average NYMEX price was $82.72 per barrel, adjusted to $74.13 per barrel at the wellhead. As a result of continued low commodity prices during the second quarter of 2015, we recorded a $94 million pre-tax non-cash impairment of oil and gas assets. For natural gas, the average NYMEX price was $3.39 per Mcf, adjusted to $2.14 per Mcf at the wellhead; for crude oil, the average NYMEX price was $71.68 per barrel, adjusted to $63.76 per barrel at the wellhead. Equity investments in unconsolidated subsidiaries Our Oil and Gas segment owns a 25% interest in a pipeline and gathering system, accounted for under the equity method of accounting. Due to sustained low commodity prices, recurring operating losses and future expectations we reviewed this investment interest for impairment utilizing the other-than-temporary impairment model under ASC 820, Fair Value Measurements. We valued this investment applying a market method approach utilizing assumptions consistent with similar known and measurable transactions. The carrying amount of this equity method investment exceeded the fair value, and we concluded the decline is considered to be other than temporary. As a result we recorded a pre-tax impairment loss at June 30, 2015 of $5.2 million, the difference between the carrying amount and the fair value of the investment.

Management's Statement: Correction of Immaterial Errors (Tables)

6 Months Ended

Jun. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]

The impact of the errors relate entirely to our Oil and Gas segment.

CONDENSED CONSOLIDATED STATEMENTS OF INCOME



	For the Three Months Ended June 30, 2014									For the Six Months Ended June 30, 2014
	As Reported			Adjustments			As Revised			As Reported			Adjustments			As Revised
	(in thousands expect per share amounts)

Depreciation, depletion and amortization	$	36,712		$	(835	)	$	35,877		$	72,795		$	(1,669	)	$	71,126
Total operating expenses	$	236,660		$	(835	)	$	235,825		$	607,231		$	(1,669	)	$	605,562

Operating income (loss)	$	46,577		$	835		$	47,412		$	136,175		$	1,669		$	137,844

Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	$	30,471		$	835		$	31,306		$	103,955		$	1,669		$	105,624
Income tax benefit (expense)	$	(10,651	)	$	(308	)	$	(10,959	)	$	(36,017	)	$	(615	)	$	(36,632	)
Net income (loss) available for common stock	$	19,820		$	527		$	20,347		$	67,938		$	1,054		$	68,992

Earnings (loss) per share of common stock:
Earnings (loss) per share, Basic	$	0.45		$	0.01		$	0.46		$	1.53		$	0.03		$	1.56
Earnings (loss) per share, Diluted	$	0.44		$	0.02		$	0.46		$	1.52		$	0.03		$	1.55

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)



	For the Three Months Ended June 30, 2014						For the Six Months Ended June 30, 2014
(in thousands)	As Reported		Adjustments		As Revised		As Reported		Adjustments		As Revised
Net income (loss) available for common stock	$	19,820	$	527	$	20,347	$	67,938	$	1,054	$	68,992
Comprehensive income (loss)	$	18,968	$	527	$	19,495	$	65,919	$	1,054	$	66,973

CONDENSED CONSOLIDATED BALANCE SHEET



	As of June 30, 2014
	As Reported			Adjustments			As Revised
	(in thousands)
Accumulated depreciation and depletion	$	(1,325,660	)	$	(35,573	)	$	(1,361,233	)
Total property, plant and equipment, net	$	3,082,631		$	(35,573	)	$	3,047,058
TOTAL ASSETS	$	3,970,498		$	(35,573	)	$	3,934,925

Deferred income tax liability, non-current	$	476,059		$	(12,379	)	$	463,680
Total deferred credits and other liabilities	$	853,940		$	(12,379	)	$	841,561

Retained earnings	$	573,379		$	(23,194	)	$	550,185
Total stockholders' equity	$	1,341,325		$	(23,194	)	$	1,318,131
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$	3,970,498		$	(35,573	)	$	3,934,925

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS



	Six Months Ended June 30, 2014
	As Reported		Adjustments			As Revised
	(in thousands)
Net income (loss) available for common stock	$	67,938	$	1,054		$	68,992

Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	$	72,795	$	(1,669	)	$	71,126
Deferred income taxes	$	35,514	$	615		$	36,129
Net cash provided by (used in) operating activities	$	173,835	$	—		$	173,835

The Notes to the Condensed Consolidated Financial Statements have been revised to reflect the correction of these errors for all periods presented.

Business Segment Information: Business Segment Information (Tables)

6 Months Ended

Jun. 30, 2015

Segment Reporting Information, Additional Information [Abstract]

Schedule of Segment Reporting Information

Segment information and Corporate activities included in the accompanying Condensed Consolidated Statements of Income (Loss) were as follows (in thousands):



Three Months Ended June 30, 2015	External Operating Revenue		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	169,751	$	2,509		$	17,702
Gas	79,426		—			3,165
Non-regulated Energy:
Power Generation	1,706		20,603			7,549
Coal Mining	9,052		7,673			3,049
Oil and Gas ^(a)(b)	12,319		—			(71,195		)
Corporate activities^(c)	—		—			(2,112		)
Inter-company eliminations	—		(30,785		)	—
Total	$	272,254	$	—		$	(41,842	)



Three Months Ended June 30, 2014	External Operating Revenue		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	158,740	$	3,144		$	11,427
Gas	102,499		—			1,994
Non-regulated Energy:
Power Generation	1,267		20,713			7,194
Coal Mining	5,583		9,068			2,016
Oil and Gas	15,148		—			(1,133		)
Corporate activities	—		—			(1,151		)
Inter-company eliminations	—		(32,925		)	—
Total	$	283,237	$	—		$	20,347




Six Months Ended June 30, 2015	External Operating Revenues		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	352,725	$	5,933		$	36,631
Gas	317,077		—			25,377
Non-regulated Energy:
Power Generation	3,659		41,324			15,694
Coal Mining	17,194		15,465			6,059
Oil and Gas ^(a)(b)	23,586		—			(90,310		)
Corporate activities ^(c)	—		—			(1,443		)
Inter-company eliminations	—		(62,722		)	—
Total	$	714,241	$	—		$	(7,992	)




Six Months Ended June 30, 2014	External Operating Revenues		Inter-company Operating Revenue			Net Income (Loss)
Utilities:
Electric	$	336,835	$	7,151		$	26,002
Gas	361,836		—			26,692
Non-regulated Energy:
Power Generation	2,536		41,792			15,267
Coal Mining	12,201		17,948			4,480
Oil and Gas	29,998		—			(2,628		)
Corporate activities	—		—			(821		)
Inter-company eliminations	—		(66,891		)	—
Total	$	743,406	$	—		$	68,992

__________


(a)	Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.


(b)	Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.

Reconciliation of Assets from Segment to Consolidated

Segment information and Corporate balances included in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands):



Total Assets (net of inter-company eliminations) as of:	June 30, 2015		December 31, 2014		June 30, 2014
Utilities:
Electric ^(a)	$	2,856,903	$	2,748,680	$	2,603,900
Gas	801,295		906,922		799,365
Non-regulated Energy:
Power Generation^(a)	72,270		76,945		85,269
Coal Mining	76,079		74,407		73,701
Oil and Gas ^{(b) (c)}	275,068		332,343		272,264
Corporate activities	138,656		106,605		100,426
Total assets	$	4,220,271	$	4,245,902	$	3,934,925

__________


(a)	The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease.


(b)	As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.


(c)	Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015.

Accounts Receivable: Accounts Receivable (Tables)

6 Months Ended

Jun. 30, 2015

Receivables [Abstract]

Accounts Receivable and Allowance for Doubtful Accounts

Following is a summary of Accounts receivable, net included in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	Accounts		Unbilled		Less Allowance for			Accounts
June 30, 2015	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	46,381	$	33,501	$	(685	)	$	79,197
Gas Utilities	25,635		9,418		(1,259		)	33,794
Power Generation	1,199		—		—			1,199
Coal Mining	3,402		—		—			3,402
Oil and Gas	5,099		—		(13		)	5,086
Corporate	983		—		—			983
Total	$	82,699	$	42,919	$	(1,957	)	$	123,661



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2014	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	59,714	$	26,474	$	(722	)	$	85,466
Gas Utilities	47,394		45,546		(781		)	92,159
Power Generation	1,369		—		—			1,369
Coal Mining	3,151		—		—			3,151
Oil and Gas	5,305		—		(13		)	5,292
Corporate	2,555		—		—			2,555
Total	$	119,488	$	72,020	$	(1,516	)	$	189,992



	Accounts		Unbilled		Less Allowance for			Accounts
June 30, 2014	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	48,333	$	21,716	$	(622	)	$	69,427
Gas Utilities	43,104		9,265		(1,027		)	51,342
Power Generation	1,388		—		—			1,388
Coal Mining	1,866		—		—			1,866
Oil and Gas	9,123		—		(13		)	9,110
Corporate	2,012		—		—			2,012
Total	$	105,826	$	30,981	$	(1,662	)	$	135,145

Regulatory Accounting: Regulatory Assets and Liabilities (Tables)

6 Months Ended

Jun. 30, 2015

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets and Liabilities

We had the following regulatory assets and liabilities (in thousands):



	Maximum	As of		As of		As of
	Amortization (in years)	June 30, 2015		December 31, 2014		June 30, 2014
Regulatory assets
Deferred energy and fuel cost adjustments - current^{(a) (d)}	1	$	26,862	$	23,820	$	29,605
Deferred gas cost adjustments ^(a)(d)	2	5,588		37,471		35,479
Gas price derivatives ^(a)	7	17,907		18,740		3,561
AFUDC^(b)	45	12,321		12,358		12,468
Employee benefit plans ^{(c) (e)}	12	96,734		97,126		65,874
Environmental^(a)	subject to approval	1,224		1,314		1,314
Asset retirement obligations^(a)	44	3,242		3,287		3,278
Bond issue cost^(a)	23	3,204		3,276		3,347
Renewable energy standard adjustment ^(a)	5	5,629		9,622		14,501
Flow through accounting^(c)	35	27,861		25,887		22,754
Decommissioning costs ^(f)	10	14,845		12,484		—
Other regulatory assets^(a)	15	12,555		12,454		10,780
		$	227,972	$	257,839	$	202,961

Regulatory liabilities
Deferred energy and gas costs^{(a) (d)}	1	$	16,114	$	6,496	$	6,490
Employee benefit plans^{(c) (e)}	12	53,163		53,139		34,356
Cost of removal^(a)	44	84,118		78,249		70,841
Other regulatory liabilities^(c)	25	8,350		10,947		8,603
		$	161,745	$	148,831	$	120,290

__________


(a)	Recovery of costs, but we are not allowed a rate of return.


(b)	In addition to recovery of costs, we are allowed a rate of return.


(c)	In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively.

(d)


(e)	Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.


(f)	Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

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

6 Months Ended

Jun. 30, 2015

Inventory, Net [Abstract]

Materials, Supplies and Fuel

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



	June 30, 2015		December 31, 2014		June 30, 2014
Materials and supplies	$	54,646	$	49,555	$	51,925
Fuel - Electric Utilities	6,644		6,637		7,679
Natural gas in storage held for distribution	12,459		34,999		21,560
Total materials, supplies and fuel	$	73,749	$	91,191	$	81,164

Earnings Per Share: Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2015

Earnings Per Share [Abstract]

Schedule of Earnings Per Share Reconciliation

A reconciliation of share amounts used to compute Earnings (loss) per share in the accompanying Condensed Consolidated Statements of Income (loss) was as follows (in thousands):



	Three Months Ended June 30,					Six Months Ended June 30,
	2015			2014		2015			2014

Net income (loss) available for common stock	$	(41,842	)	$	20,347	$	(7,992	)	$	68,992

Weighted average shares - basic	44,617			44,399		44,579			44,365
Dilutive effect of:
Equity compensation	—			189		—			206
Weighted average shares - diluted	44,617			44,588		44,579			44,571

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share



	Three Months Ended June 30,		Six Months Ended June 30,
	2015	2014	2015	2014

Equity compensation	119	81	113	63
Anti-dilutive shares	119	81	113	63

Notes Payable and Long-term Debt: Notes Payable and Long-term Debt (Tables)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Schedule of Short-term Debt

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



	June 30, 2015				December 31, 2014				June 30, 2014
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	105,760	$	23,100	$	75,000	$	35,000	$	132,700	$	20,272

Schedule of Credit Facility Covenants

Our Revolving Credit Facility and our Term Loan require compliance with the following financial covenant at the end of each quarter:



	As of June 30, 2015	Covenant Requirement
Recourse Leverage Ratio	57%	Less than	65%

Risk Management Activities: Risk Management Activities (Tables)

6 Months Ended

Jun. 30, 2015

Derivative [Line Items]

Schedule of Derivative Instruments

The contract or notional amounts, terms of our interest rate swaps and the interest rate swaps balances reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of:



	June 30, 2015			December 31, 2014			June 30, 2014
	Interest Rate Swaps^(a)			Interest Rate Swaps^(a)			Interest Rate Swaps^(a)
Notional	$	75,000		$	75,000		$	75,000
Weighted average fixed interest rate	4.97		%	4.97		%	4.97		%
Maximum terms in years	1.50			2.00			2.50
Derivative liabilities, current	$	3,289		$	3,340		$	3,480
Derivative liabilities, non-current	$	1,433		$	2,680		$	4,251

__________


(a)	These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings.

Derivative Instruments, Gain (Loss)

The impacts of cash flow hedges on our Condensed Consolidated Statements of Income (Loss) were as follows (in thousands):



Three Months Ended June 30, 2015
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	$	(892	)	Interest expense	$	(1,670	)		$	—
Commodity derivatives	(2,245		)	Revenue	3,666				—
Total	$	(3,137	)		$	1,996			$	—



Three Months Ended June 30, 2014
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	$	(337	)	Interest expense	$	(926	)		$	—
Commodity derivatives	(2,737		)	Revenue	(1,251		)		—
Total	$	(3,074	)		$	(2,177	)		$	—




Six Months Ended June 30, 2015
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	$	(1,778	)	Interest expense	$	(3,107	)		$	—
Commodity derivatives	1,520			Revenue	7,598				—
Total	$	(258	)		$	4,491			$	—




Six Months Ended June 30, 2014
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	$	(429	)	Interest expense	$	(1,820	)		$	—
Commodity derivatives	(6,209		)	Revenue	(1,562		)		—
Total	$	(6,638	)		$	(3,382	)		$	—

Oil and Gas [Member]

Derivative [Line Items]

Schedule of Derivative Instruments



	June 30, 2015				December 31, 2014				June 30, 2014
	Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps		Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps		Crude Oil Futures, Swaps and Options		Natural Gas Futures and Swaps
Notional ^(a)	276,000		4,187,500		334,500		6,582,500		424,500		9,265,000
Maximum terms in months ^(b)	1		1		1		1		1		1
Derivative assets, current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative assets, non-current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative liabilities, current	$	—	$	—	$	—	$	—	$	—	$	—
Derivative liabilities, non-current	$	—	$	—	$	—	$	—	$	—	$	—

__________


(a)	Crude oil in Bbls, natural gas in MMBtus.


(b)	Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument.

Utilities Group [Member]

Derivative [Line Items]

Schedule of Derivative Instruments

We had the following derivative balances related to the hedges in our Utilities reflected in our Condensed Consolidated Balance Sheets as of (in thousands):



	June 30, 2015		December 31, 2014		June 30, 2014
Derivative assets, current	$	—	$	—	$	1,737
Derivative assets, non-current	$	—	$	—	$	—
Derivative liabilities, non-current	$	—	$	—	$	—
Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities	$	17,907	$	18,740	$	3,561

Contract or Notional Amounts and Terms of Commodity Derivatives

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



	June 30, 2015		December 31, 2014		June 30, 2014
	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)
Natural gas futures purchased	17,270,000	66	19,370,000	72	16,240,000	78
Natural gas options purchased	3,980,000	9	4,020,000	8	3,980,000	9
Natural gas basis swaps purchased	14,445,000	54	12,005,000	60	13,415,000	66

__________

(a) Term reflects the maximum forward period hedged.

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41641-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41638-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579240-113959

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41620-113959

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Fair Value Measurements: Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Schedule of Fair Value Hierarchy, Measured on Recurring Basis



	As of June 30, 2015
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		5,178		—		(5,178		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		4,372		—		(4,372		)	—
Commodity derivatives — Utilities	—		2,577		—		(2,577		)	—
Total	$	—	$	12,127	$	—	$	(12,127	)	$	—

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		112		—		(112		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		498		—		(498		)	—
Commodity derivatives — Utilities	—		18,758		—		(18,758		)	—
Interest rate swaps	—		4,722		—		—			4,722
Total	$	—	$	24,090	$	—	$	(19,368	)	$	4,722



	As of December 31, 2014
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		8,599		—		(8,599		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		6,558		—		(6,558		)	—
Commodity derivatives —Utilities	—		2,389		—		(2,389		)	—
Total	$	—	$	17,546	$	—	$	(17,546	)	$	—

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		—		—		—			—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		473		—		(473		)	—
Commodity derivatives — Utilities	—		19,303		—		(19,303		)	—
Interest rate swaps	—		6,020		—		—			6,020
Total	$	—	$	25,796	$	—	$	(19,776	)	$	6,020



	As of June 30, 2014
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		—		—		—			—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		600		—		(600		)	—
Commodity derivatives — Utilities	—		4,342		—		(2,605		)	1,737
Total	$	—	$	4,942	$	—	$	(3,205	)	$	1,737

Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—	$	—	$	—	$	—		$	—
Basis Swaps -- Oil	—		4,020		—		(4,020		)	—
Options -- Gas	—		—		—		—			—
Basis Swaps -- Gas	—		2,030		—		(2,030		)	—
Commodity derivatives — Utilities	—		5,989		—		(5,989		)	—
Interest rate swaps	—		7,731		—		—			7,731
Total	$	—	$	19,770	$	—	$	(12,039	)	$	7,731

Schedule of Derivative Instruments Balance Sheet Location

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



As of June 30, 2015
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	6,931	$	—
Commodity derivatives	Derivative assets — non-current	2,619		—
Commodity derivatives	Derivative liabilities — current	—		493
Commodity derivatives	Derivative liabilities — non-current	—		117
Interest rate swaps	Derivative liabilities — current	—		3,289
Interest rate swaps	Derivative liabilities — non-current	—		1,433
Total derivatives designated as hedges		$	9,550	$	5,332

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		5,156
Commodity derivatives	Derivative liabilities — non-current	—		11,025
Total derivatives not designated as hedges		$	—	$	16,181



As of December 31, 2014
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	10,391	$	—
Commodity derivatives	Derivative assets — non-current	4,766		—
Commodity derivatives	Derivative liabilities — current	—		185
Commodity derivatives	Derivative liabilities — non-current	—		288
Interest rate swaps	Derivative liabilities — current	—		3,340
Interest rate swaps	Derivative liabilities — non-current	—		2,680
Total derivatives designated as hedges		$	15,157	$	6,493

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	—	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		8,032
Commodity derivatives	Derivative liabilities — non-current	—		8,882
Total derivatives not designated as hedges		$	—	$	16,914



As of June 30, 2014
	Balance Sheet Location	Fair Value of Asset Derivatives		Fair Value of Liability Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current	$	262	$	—
Commodity derivatives	Derivative assets — non-current	338		—
Commodity derivatives	Derivative liabilities — current	—		3,702
Commodity derivatives	Derivative liabilities — non-current	—		2,348
Interest rate swaps	Derivative liabilities — current	—		3,480
Interest rate swaps	Derivative liabilities — non-current	—		4,251
Total derivatives designated as hedges		$	600	$	13,781

Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current	$	1,737	$	—
Commodity derivatives	Derivative assets — non-current	—		—
Commodity derivatives	Derivative liabilities — current	—		—
Commodity derivatives	Derivative liabilities — non-current	—		3,384
Total derivatives not designated as hedges		$	1,737	$	3,384

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

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

The estimated fair values of our financial instruments, excluding derivatives which are presented in Note 10, were as follows (in thousands) as of:



	June 30, 2015				December 31, 2014				June 30, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
Cash and cash equivalents ^(a)	$	87,210	$	87,210	$	21,218	$	21,218	$	14,697	$	14,697
Restricted cash and equivalents ^(a)	$	2,316	$	2,316	$	2,056	$	2,056	$	2	$	2
Notes payable ^(a)	$	105,760	$	105,760	$	75,000	$	75,000	$	132,700	$	132,700
Long-term debt, including current maturities ^(b)	$	1,567,727	$	1,700,487	$	1,542,589	$	1,734,555	$	1,396,950	$	1,578,756

__________


(a)	Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy.


(b)	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.

Other Comprehensive Income (Loss): Other Comprehensive Income (Loss) (Tables)

6 Months Ended

Jun. 30, 2015

Statement of Comprehensive Income [Abstract]

Reclassification Out of Accumulated Other Comprehensive Income (Loss)

The components of the reclassification adjustments, net of tax, included in Other Comprehensive Income (Loss) for the periods were as follows (in thousands):



	Location on the Condensed Consolidated Statements of Income (Loss)	Amount Reclassified from AOCI
		Three Months Ended						Six Months Ended
		June 30, 2015			June 30, 2014			June 30, 2015			June 30, 2014
Gains (losses) on cash flow hedges:
Interest rate swaps	Interest expense	$	1,670		$	926		$	3,107		$	1,820
Commodity contracts	Revenue	(3,666		)	1,251			(7,598		)	1,562
		(1,996		)	2,177			(4,491		)	3,382
Income tax	Income tax benefit (expense)	735			(774		)	1,989			(1,199		)
Reclassification adjustments related to cash flow hedges, net of tax		$	(1,261	)	$	1,403		$	(2,502	)	$	2,183

Amortization of defined benefit plans:
Prior service cost	Utilities - Operations and maintenance	$	(26	)	$	(25	)	$	(53	)	$	(51	)
	Non-regulated energy operations and maintenance	(29		)	(84		)	(57		)	(71		)

Actuarial gain (loss)	Utilities - Operations and maintenance	454			158			908			315
	Non-regulated energy operations and maintenance	251			101			502			186
		650			150			1,300			379
Income tax	Income tax benefit (expense)	(228		)	(52		)	(456		)	(133		)
Reclassification adjustments related to defined benefit plans, net of tax		$	422		$	98		$	844		$	246

Schedule of 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, 2013	$	(7,133	)	$	(10,289	)	$	(17,422	)
Other comprehensive income (loss), net of tax	(1,478		)	311			(1,167		)
Balance as of March 31, 2014	(8,611		)	(9,978		)	(18,589		)
Other comprehensive income (loss), net of tax	(556		)	(296		)	(852		)
Balance as of June 30, 2014	$	(9,167	)	$	(10,274	)	$	(19,441	)

Balance as of December 31, 2014	$	5,093		$	(20,137	)	$	(15,044	)
Other comprehensive income (loss), net of tax	595			395			990
Balance as of March 31, 2015	5,688			(19,742		)	(14,054		)
Other comprehensive income (loss), net of tax	422			(3,227		)	(2,805		)
Balance as of June 30, 2015	$	6,110		$	(22,969	)	$	(16,859	)

Supplemental Disclosure of Cash Flow Information: Supplemental Disclosure of Cash Flow Information (Tables)

6 Months Ended

Jun. 30, 2015

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information



Six months ended	June 30, 2015			June 30, 2014
	(in thousands)
Non-cash investing and financing activities from continuing operations—
Property, plant and equipment acquired with accrued liabilities	$	36,661		$	40,611
Increase (decrease) in capitalized assets associated with asset retirement obligations	$	—		$	(2,785	)

Cash (paid) refunded during the period for continuing operations—
Interest (net of amounts capitalized)	$	(37,698	)	$	(35,009	)
Income taxes, net	$	(1,202	)	$	(396	)

Employee Benefit Plans: Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2015

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Schedule of Net Benefit Costs

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Service cost	$	1,494		$	1,362		$	2,988		$	2,724
Interest cost	3,880			3,963			7,760			7,926
Expected return on plan assets	(4,867		)	(4,516		)	(9,734		)	(9,032		)
Prior service cost	15			16			30			32
Net loss (gain)	2,759			1,201			5,518			2,403
Net periodic benefit cost	$	3,281		$	2,026		$	6,562		$	4,053

Defined Benefit Postretirement Healthcare Plans

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Service cost	$	464		$	425		$	928		$	850
Interest cost	450			480			900			959
Expected return on plan assets	(33		)	(21		)	(66		)	(42		)
Prior service cost (benefit)	(107		)	(107		)	(214		)	(214		)
Net loss (gain)	102			40			204			80
Net periodic benefit cost	$	876		$	817		$	1,752		$	1,633

Supplemental Non-qualified Defined Benefit and Defined Contribution Plans

The components of net periodic benefit cost for the Supplemental Non-qualified Defined Benefit and Defined Contribution Plans were as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Service cost	$	392	$	374	$	883	$	749
Interest cost	364		362		728		724
Prior service cost	1		1		2		1
Net loss (gain)	270		124		540		249
Net periodic benefit cost	$	1,027	$	861	$	2,153	$	1,723

Schedule of Defined Benefit Plans Contributions

Contributions and anticipated contributions are as follows (in thousands):



	Contributions Made		Contributions Made		Additional Contributions		Contributions
	Three Months Ended June 30, 2015		Six Months Ended June 30, 2015		Anticipated for 2015		Anticipated for 2016
Defined Benefit Pension Plans	$	—	$	—	$	10,200	$	10,200
Non-pension Defined Benefit Postretirement Healthcare Plans	$	939	$	1,878	$	1,877	$	4,026
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	372	$	744	$	743	$	1,544

Management's Statement: Correction of Immaterial Errors (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Statement [Abstract]
Depreciation, depletion and amortization	$ 40,051	$ 35,877	$ 79,053	$ 71,126
Total operating expenses	311,112	235,825	682,599	605,562
Operating income (loss)	(38,858)	47,412	31,642	137,844
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	(56,942)	31,306	(5,083)	105,624
Income tax expense (benefit)	20,317	(10,959)	2,605	(36,632)
Net income (loss) available for common stock	$ (41,842)	$ 20,347	$ (7,992)	$ 68,992
Total income (loss) per share, Basic	$ (0.94)	$ 0.46	$ (0.18)	$ 1.56
Total income (loss) per share, Diluted	$ (0.94)	$ 0.46	$ (0.18)	$ 1.55
Comprehensive income (loss)	$ (44,647)	$ 19,495	$ (9,807)	$ 66,973
Balance Sheet [Abstract]
Accumulated depreciation and depletion	(1,522,969)	(1,361,233)	(1,522,969)	(1,361,233)	$ (1,357,929)
Total property, plant and equipment, net	3,203,509	3,047,058	3,203,509	3,047,058	3,205,471
Total Assets	4,220,271	3,934,925	4,220,271	3,934,925	4,245,902
Deferred income tax liabilities, net, non-current	510,435	463,680	510,435	463,680	511,952
Total deferred credits and other liabilities	983,150	841,561	983,150	841,561	973,148
Retained earnings	532,965	550,185	532,965	550,185	577,249
Total stockholders’ equity	1,310,886	1,318,131	1,310,886	1,318,131	1,353,884
Total Liabilities and Stockholders' Equity	$ 4,220,271	3,934,925	4,220,271	3,934,925	$ 4,245,902
Statement of Cash Flows [Abstract]
Net Cash Provided by (Used in) Operating Activities			254,408	173,835
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income taxes			$ (6,277)	36,129
Scenario, Previously Reported [Member]
Income Statement [Abstract]
Depreciation, depletion and amortization		36,712		72,795
Total operating expenses		236,660		607,231
Operating income (loss)		46,577		136,175
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes		30,471		103,955
Income tax expense (benefit)		(10,651)		(36,017)
Net income (loss) available for common stock		$ 19,820		$ 67,938
Total income (loss) per share, Basic		$ 0.45		$ 1.53
Total income (loss) per share, Diluted		$ 0.44		$ 1.52
Comprehensive income (loss)		$ 18,968		$ 65,919
Balance Sheet [Abstract]
Accumulated depreciation and depletion		(1,325,660)		(1,325,660)
Total property, plant and equipment, net		3,082,631		3,082,631
Total Assets		3,970,498		3,970,498
Deferred income tax liabilities, net, non-current		476,059		476,059
Total deferred credits and other liabilities		853,940		853,940
Retained earnings		573,379		573,379
Total stockholders’ equity		1,341,325		1,341,325
Total Liabilities and Stockholders' Equity		3,970,498		3,970,498
Statement of Cash Flows [Abstract]
Net Cash Provided by (Used in) Operating Activities				173,835
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income taxes				35,514
Scenario, Adjustment [Member]
Income Statement [Abstract]
Depreciation, depletion and amortization		(835)		(1,669)
Total operating expenses		(835)		(1,669)
Operating income (loss)		835		1,669
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes		835		1,669
Income tax expense (benefit)		(308)		(615)
Net income (loss) available for common stock		$ 527		$ 1,054
Total income (loss) per share, Basic		$ 0.01		$ 0.03
Total income (loss) per share, Diluted		$ 0.02		$ 0.03
Comprehensive income (loss)		$ 527		$ 1,054
Balance Sheet [Abstract]
Accumulated depreciation and depletion		(35,573)		(35,573)
Total property, plant and equipment, net		(35,573)		(35,573)
Total Assets		(35,573)		(35,573)
Deferred income tax liabilities, net, non-current		(12,379)		(12,379)
Total deferred credits and other liabilities		(12,379)		(12,379)
Retained earnings		(23,194)		(23,194)
Total stockholders’ equity		(23,194)		(23,194)
Total Liabilities and Stockholders' Equity		$ (35,573)		(35,573)
Statement of Cash Flows [Abstract]
Net Cash Provided by (Used in) Operating Activities				0
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Deferred income taxes				$ 615

Subsequent Event: Subsequent Event (Details) customer in Thousands, $ in Thousands		6 Months Ended
	Jul. 12, 2015 USD ($) customer utility	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Aug. 06, 2015 USD ($)
Common stock issued		$ 1,702	$ 1,693
Revolving Credit Facility [Member]
Debt covenant, maximum recourse ratio		0.65
Subsequent Event [Member] \| Source Gas [Member]
Acquisition purchase price	$ 1,890,000
Included in purchase price - projected capital expenditures through closing	200,000
Included in purchase price - long-term debt to be assumed	720,000
Projected net purchase price	1,740,000
Included in purchase price - tax benefits	150,000
Bridge facility	1,170,000			$ 1,170,000
Subsequent Event [Member] \| Source Gas [Member] \| Bridge Loan [Member]
Debt covenant, maximum recourse ratio				0.75
Subsequent Event [Member] \| Source Gas [Member] \| Revolving Credit Facility [Member]
Debt covenant, maximum recourse ratio				0.65
Debt covenant, aggregate outstanding debt assumed or incurred, amount				$ 1,460,000
Subsequent Event [Member] \| Source Gas [Member] \| Minimum [Member]
Proceeds from Issuance of Debt	450,000
Common stock issued	575,000
Subsequent Event [Member] \| Source Gas [Member] \| Minimum [Member] \| Revolving Credit Facility [Member]
Debt covenant, aggregate outstanding debt assumed or incurred, amount				1,250,000
Subsequent Event [Member] \| Source Gas [Member] \| Maximum [Member]
Proceeds from Issuance of Debt	550,000
Common stock issued	$ 675,000
Subsequent Event [Member] \| Source Gas [Member] \| Maximum [Member] \| Revolving Credit Facility [Member]
Debt covenant, aggregate outstanding debt assumed or incurred, amount				$ 1,460,000
Source Gas [Member] \| Subsequent Event [Member]
Number of regulated natural gas utilities, acquiree \| utility	4
Number of customers served by acquiree \| customer	425
Aggregate Outstanding Debt Assumed and Incurred of $1.25 billion to $1.46 billion [Member] \| Subsequent Event [Member] \| Revolving Credit Facility [Member]
Debt covenant, maximum recourse ratio				0.70
Aggregate Outstanding Debt Assumed or Incurred Exceeding $1.46 billion [Member] \| Subsequent Event [Member] \| Source Gas [Member] \| Revolving Credit Facility [Member]
Debt covenant, maximum recourse ratio				0.75

Business Segment Information: Information Relating to Segment Statement of Income (Details) - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2015

Jun. 30, 2014

Jun. 30, 2015

Jun. 30, 2014

Segment Reporting Information

Non-cash impairment of our Oil and Gas equity investments

$ 5,170

$ 0

$ 5,170

$ 0

Revenue

272,254

283,237

714,241

743,406

Net Income (Loss)

(41,842)

20,347

(7,992)

68,992

Inter-company eliminations [Member]

Segment Reporting Information

Revenue

(30,785)

(32,925)

(62,722)

(66,891)

Net Income (Loss)

Corporate activities[Member]

Segment Reporting Information

Revenue

Net Income (Loss)

(2,112)

^[1]

(1,151)

(1,443)

^[1]

(821)

Consolidation, Eliminations [Member]

Segment Reporting Information

Revenue

Electric Utilities [Member]

Segment Reporting Information

Revenue

169,751

158,740

352,725

336,835

Net Income (Loss)

17,702

11,427

36,631

26,002

Electric Utilities [Member] | Inter-company eliminations [Member]

Segment Reporting Information

Revenue

2,509

3,144

5,933

7,151

Gas Utilities [Member]

Segment Reporting Information

Revenue

79,426

102,499

317,077

361,836

Net Income (Loss)

3,165

1,994

25,377

26,692

Gas Utilities [Member] | Inter-company eliminations [Member]

Segment Reporting Information

Revenue

Power Generation [Member]

Segment Reporting Information

Revenue

1,706

1,267

3,659

2,536

Net Income (Loss)

7,549

7,194

15,694

15,267

Power Generation [Member] | Inter-company eliminations [Member]

Segment Reporting Information

Revenue

20,603

20,713

41,324

41,792

Coal Mining [Member]

Segment Reporting Information

Revenue

9,052

5,583

17,194

12,201

Net Income (Loss)

3,049

2,016

6,059

4,480

Coal Mining [Member] | Inter-company eliminations [Member]

Segment Reporting Information

Revenue

7,673

9,068

15,465

17,948

Oil and Gas [Member]

Segment Reporting Information

Non-cash impairment of our Oil and Gas equity investments

5,170

Revenue

12,319

15,148

23,586

29,998

Net Income (Loss)

(71,195)

^[2],[3]

(1,133)

(90,310)

^[2],[3]

(2,628)

Impairment of Oil and Gas Properties Net of Tax

77,000

63,000

Equity Method Investment, Other than Temporary Impairment, Net of Income Taxes

3,400

Oil and Gas [Member] | Inter-company eliminations [Member]

Segment Reporting Information

Revenue

$ 0

Net of Tax [Member] | Corporate activities[Member]

Segment Reporting Information

Business Acquisition, Transaction Costs

$ 500

$ 300

[1]	Net income (loss) for the three and six months ended June 30, 2015 included acquisition costs, net of tax of $0.5 million and $0.3 million, respectively. See Note 2 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[2]	Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[3]	Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.

Business Segment Information: Segment and Corporate Assets (Details) - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2015

Mar. 31, 2015

Jun. 30, 2014

Jun. 30, 2015

Jun. 30, 2014

Dec. 31, 2014

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

$ 4,220,271

$ 3,934,925

$ 4,220,271

$ 3,934,925

$ 4,245,902

Impairment of Oil and Gas Properties

121,690

Non-cash impairment of our Oil and Gas equity investments

5,170

Corporate activities[Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

138,656

100,426

138,656

100,426

106,605

Electric Utilities [Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

^[1]

2,856,903

2,603,900

2,856,903

2,603,900

2,748,680

Gas Utilities [Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

801,295

799,365

801,295

799,365

906,922

Power Generation [Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

^[1]

72,270

85,269

72,270

85,269

76,945

Coal Mining [Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

76,079

73,701

76,079

73,701

74,407

Oil and Gas [Member]

Segment Reporting, Asset Reconciling Item [Line Items]

Assets

275,068

^[2],[3]

$ 272,264

275,068

^[2],[3]

$ 272,264

$ 332,343

Impairment of Oil and Gas Properties

$ 94,000

$ 22,000

117,000

Non-cash impairment of our Oil and Gas equity investments

$ 5,170

[1]	The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease.
[2]	As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[3]	Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015.

Accounts Receivable: Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	$ (1,957)	$ (1,516)	$ (1,662)
Accounts receivable, net	123,661	189,992	135,145
Corporate[Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	983	2,555	2,012
Electric Utilities [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	(685)	(722)	(622)
Accounts receivable, net	79,197	85,466	69,427
Gas Utilities [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	(1,259)	(781)	(1,027)
Accounts receivable, net	33,794	92,159	51,342
Power Generation [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	1,199	1,369	1,388
Coal Mining [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	3,402	3,151	1,866
Oil and Gas [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	(13)	(13)	(13)
Accounts receivable, net	5,086	5,292	9,110
Billed Revenues [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	82,699	119,488	105,826
Billed Revenues [Member] \| Corporate[Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	983	2,555	2,012
Billed Revenues [Member] \| Electric Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	46,381	59,714	48,333
Billed Revenues [Member] \| Gas Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	25,635	47,394	43,104
Billed Revenues [Member] \| Power Generation [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	1,199	1,369	1,388
Billed Revenues [Member] \| Coal Mining [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	3,402	3,151	1,866
Billed Revenues [Member] \| Oil and Gas [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	5,099	5,305	9,123
Unbilled Revenues [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	42,919	72,020	30,981
Unbilled Revenues [Member] \| Corporate[Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	0	0	0
Unbilled Revenues [Member] \| Electric Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	33,501	26,474	21,716
Unbilled Revenues [Member] \| Gas Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	9,418	45,546	9,265
Unbilled Revenues [Member] \| Power Generation [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	0	0	0
Unbilled Revenues [Member] \| Coal Mining [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	0	0	0
Unbilled Revenues [Member] \| Oil and Gas [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	$ 0	$ 0	$ 0

Regulatory Accounting: Regulatory Assets and Liabilities (Details) - USD ($)
$ in Thousands

6 Months Ended

Jun. 30, 2015

Dec. 31, 2014

Jun. 30, 2014

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets

$ 227,972

$ 257,839

$ 202,961

Regulatory Liabilities

$ 161,745

148,831

120,290

Deferred energy and gas costs

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

1 year

Regulatory Liabilities

^[1],[2]

$ 16,114

6,496

6,490

Employee benefit plans

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

12 years

Regulatory Liabilities

^[3],[4]

$ 53,163

53,139

34,356

Cost of removal

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

44 years

Regulatory Liabilities

^[2]

$ 84,118

78,249

70,841

Other regulatory liabilities

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

25 years

Regulatory Liabilities

^[3]

$ 8,350

10,947

8,603

Deferred energy and gas costs

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

1 year

Regulatory Assets

^[1],[2]

$ 26,862

23,820

29,605

Deferred gas cost adjustments

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

2 years

Regulatory Assets

^[1],[2]

$ 5,588

37,471

35,479

Gas price derivatives

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

7 years

Regulatory Assets

^[2]

$ 17,907

18,740

3,561

AFUDC

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

45 years

Regulatory Assets

^[5]

$ 12,321

12,358

12,468

Employee benefit plans

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

12 years

Regulatory Assets

^[3],[4]

$ 96,734

97,126

65,874

Environmental

Schedule Of Regulatory Assets And Liabilities [Line Items]

Regulatory Assets

^[2]

$ 1,224

1,314

Asset retirement obligations

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

44 years

Regulatory Assets

^[2]

$ 3,242

3,287

3,278

Bond issue cost

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

23 years

Regulatory Assets

^[2]

$ 3,204

3,276

3,347

Renewable energy standard adjustment

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

5 years

Regulatory Assets

^[2]

$ 5,629

9,622

14,501

Flow through accounting

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

35 years

Regulatory Assets

^[3]

$ 27,861

25,887

22,754

Decommissioning costs

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

10 years

Regulatory Assets

^[6]

$ 14,845

12,484

Other regulatory assets

Schedule Of Regulatory Assets And Liabilities [Line Items]

Maximum Amortization Period

15 years

Regulatory Assets

^[2]

$ 12,555

$ 12,454

$ 10,780

[1]	Our deferred energy, fuel cost, and gas cost adjustments represent the cost of electricity and gas delivered to our electric and gas utility customers that is either higher or lower than current rates and will be recovered or refunded in future rates. Fluctuations in deferred gas cost adjustments compared to the same period in the prior year are primarily due to higher natural gas prices driven by demand and market conditions from the peak winter heating season in the first part of 2014. Our electric and gas utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state utility commissions.
[2]	Recovery of costs, but we are not allowed a rate of return.
[3]	In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively.
[4]	Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.
[5]	In addition to recovery of costs, we are allowed a rate of return.
[6]	Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

Materials, Supplies and Fuel: Materials, Supplies and Fuel (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Inventory, Net [Abstract]
Materials and supplies	$ 54,646	$ 49,555	$ 51,925
Fuel - Electric Utilities	6,644	6,637	7,679
Natural gas in storage held for distribution	12,459	34,999	21,560
Total materials, supplies and fuel	$ 73,749	$ 91,191	$ 81,164

Earnings Per Share: Earnings Per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income (loss) available for common stock	$ (41,842)	$ 20,347	$ (7,992)	$ 68,992
Weighted average shares - basic	44,617	44,399	44,579	44,365
Dilutive effect of:
Equity compensation	0	189	0	206
Weighted average shares - diluted	44,617	44,588	44,579	44,571

Earnings Per Share: Anti-dilutive shares (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities Excluded From Diluted Earnings Per Share Due to Net Loss	83,613		101,146
Anti-dilutive shares	119,000	81,000	113,000	63,000
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares	119,000	81,000	113,000	63,000

Notes Payable and Long-term Debt: Notes Payable (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)
Revolving Credit Facility [Line Items]
Balance Outstanding	$ 105,760	$ 75,000	$ 132,700
Revolving Credit Facility [Member]
Revolving Credit Facility [Line Items]
Balance Outstanding	105,760	75,000	132,700
Letters of Credit	23,100	$ 35,000	$ 20,272
Current Borrowing Capacity	$ 500,000
Expiration Date	Jun. 26, 2020
Maximum Borrowing Capacity	$ 750,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.175%
Debt Covenants Disclosure [Abstract]
Covenant Requirement - Recourse Leverage Ratio, Actual	57.00%
Debt covenant, maximum recourse ratio	0.65
Revolving Credit Facility [Member] \| Base Rate [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	0.125%
Revolving Credit Facility [Member] \| Eurodollar [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	1.125%
Revolving Credit Facility [Member] \| Letter of Credit [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	1.125%

Notes Payable and Long-term Debt: Refinancing of Debt (Details) - Black Hills Corporation [Member] $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)
Corporate Term Loan Due June 2015 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 275
Corporate Term Loan Due April 2017 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis Spread on Variable Rate	0.90%
Corporate Debt Securities [Member] \| Corporate Term Loan Due April 2017 [Member]
Debt Instrument [Line Items]
Additional debt used for general corporate purposes	$ 25
Corporate Debt Securities [Member] \| Corporate Term Loan Due April 2017 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 300
Debt Instrument, Maturity Date	Apr. 12, 2017

Risk Management Activities: Risk Management Activities (Details)
$ in Thousands

6 Months Ended

12 Months Ended

Jun. 30, 2015

USD ($)

MMBTU

bbl

Jun. 30, 2014

USD ($)

MMBTU

bbl

Dec. 31, 2014

USD ($)

MMBTU

bbl

Derivative [Line Items]

Derivative assets, current

$ 0

$ 1,737

$ 0

Derivative liabilities, current

3,289

3,480

3,340

Derivative liabilities, non-current

1,433

4,251

2,680

Oil and Gas [Member]

Derivative [Line Items]

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

6,400

Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]

Derivative [Line Items]

Derivative liabilities, current

3,289

3,480

3,340

Derivative liabilities, non-current

1,433

4,251

2,680

Notional Amount

^[1]

$ 75,000

Weighted average fixed interest rate

4.97%

Maximum Term

1 year 6 months

2 years 6 months

2 years

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

$ (3,300)

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

Derivative [Line Items]

Notional amount - commodities | bbl

^[2]

276,000

424,500

334,500

Maximum Term Hedged in Cash Flow Hedge

^[3]

1 month

Derivative assets, current

$ 0

Derivative assets, non-current

Derivative liabilities, current

Derivative liabilities, non-current

$ 0

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

Derivative [Line Items]

Notional amount - commodities | MMBTU

^[2]

4,187,500

9,265,000

6,582,500

Maximum Term Hedged in Cash Flow Hedge

^[3]

1 month

Derivative assets, current

$ 0

Derivative assets, non-current

Derivative liabilities, current

Derivative liabilities, non-current

Utilities Group [Member] | Natural Gas, Distribution [Member]

Derivative [Line Items]

Derivative assets, current

1,737

Derivative assets, non-current

Derivative liabilities, non-current

Net Unrealized (Gain) Loss Included in Regulatory assets or Regulatory liabilities

$ 17,907

$ 3,561

$ 18,740

Utilities Group [Member] | Natural Gas, Distribution [Member] | Future [Member] | Purchase Contract [Member]

Derivative [Line Items]

Notional amount - commodities | MMBTU

17,270,000

16,240,000

19,370,000

Maximum Term

^[4]

66 months

78 months

72 months

Utilities Group [Member] | Natural Gas, Distribution [Member] | Commodity Option [Member] | Purchase Contract [Member]

Derivative [Line Items]

Notional amount - commodities | MMBTU

3,980,000

4,020,000

Maximum Term

^[4]

9 months

8 months

Utilities Group [Member] | Natural Gas, Distribution [Member] | Basis Swap [Member] | Purchase Contract [Member]

Derivative [Line Items]

Notional amount - commodities | MMBTU

14,445,000

13,415,000

12,005,000

Maximum Term

^[4]

54 months

66 months

60 months

[1]	These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings.
[2]	Crude oil in Bbls, natural gas in MMBtus.
[3]	Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument.
[4]	Term reflects the maximum forward period hedged.

Risk Management Activities: Hedging Activities (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	$ (3,137)	$ (3,074)	$ (258)	$ (6,638)
Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)	1,996	(2,177)	4,491	(3,382)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0	0	0
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	(892)	(337)	(1,778)	(429)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0	0	0
Interest Rate Swap [Member] \| Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)	(1,670)	(926)	(3,107)	(1,820)
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	(2,245)	(2,737)	1,520	(6,209)
Commodity Contract [Member] \| Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)	3,666	(1,251)	7,598	(1,562)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements: Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Assets-Transfers out of level 1 to 2	$ 0	$ 0	$ 0
Assets -Transfers out of level 2 to 1	0	0	0
Liabilities -Transfers out of level 1 to 2	0	0	0
Liabilities -Transfers out of level 2 to 1	0	0	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(12,127)	(17,546)	(3,205)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(19,368)	(19,776)	(12,039)
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	0	0	0
Derivative Liabilities, Total	0	0	0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	12,127	17,546	4,942
Derivative Liabilities, Total	24,090	25,796	19,770
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	0	0	0
Derivative Liabilities, Total	0	0	0
Interest Rate Swap [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value Disclosure	4,722	6,020	7,731
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	0	0
Interest Rate Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value Disclosure	0	0	0
Interest Rate Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value Disclosure	4,722	6,020	7,731
Interest Rate Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Fair Value Disclosure	0	0	0
Crude Oil [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	0	0	0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	0	0
Crude Oil [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Crude Oil [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Crude Oil [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Crude Oil [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(5,178)	(8,599)	0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(112)	0	(4,020)
Crude Oil [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Crude Oil [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	5,178	8,599	0
Derivative Liabilities, Fair Value Disclosure	112	0	4,020
Crude Oil [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	0	0	0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0	0	0
Natural Gas [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(4,372)	(6,558)	(600)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(498)	(473)	(2,030)
Natural Gas [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	4,372	6,558	600
Derivative Liabilities, Fair Value Disclosure	498	473	2,030
Natural Gas [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas, Distribution [Member] \| Fair Value, Measurements, Recurring [Member] \| Utilities Group [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	(2,577)	(2,389)	(2,605)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(18,758)	(19,303)	(5,989)
Natural Gas, Distribution [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Utilities Group [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Natural Gas, Distribution [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Utilities Group [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	2,577	2,389	4,342
Derivative Liabilities, Fair Value Disclosure	18,758	19,303	5,989
Natural Gas, Distribution [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Utilities Group [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Estimate of Fair Value Measurement [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	0	0	1,737
Derivative Liabilities, Total	4,722	6,020	7,731
Estimate of Fair Value Measurement [Member] \| Crude Oil [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Estimate of Fair Value Measurement [Member] \| Crude Oil [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Estimate of Fair Value Measurement [Member] \| Natural Gas [Member] \| Commodity Option [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Estimate of Fair Value Measurement [Member] \| Natural Gas [Member] \| Basis Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Oil and Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	0
Derivative Liabilities, Fair Value Disclosure	0	0	0
Estimate of Fair Value Measurement [Member] \| Natural Gas, Distribution [Member] \| Fair Value, Measurements, Recurring [Member] \| Utilities Group [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0	1,737
Derivative Liabilities, Fair Value Disclosure	$ 0	$ 0	$ 0

Fair Value Measurements: Balance Sheet Location (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Designated as Hedging Instrument [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	$ 9,550	$ 15,157	$ 600
Derivative Liability, Fair Value, Net	5,332	6,493	13,781
Not Designated as Hedging Instrument [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	0	0	1,737
Derivative Liability, Fair Value, Net	16,181	16,914	3,384
Commodity Contract [Member] \| Designated as Hedging Instrument [Member] \| Derivative Assets, Current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	6,931	10,391	262
Derivative Asset, Fair Value, Gross Liability	0	0	0
Commodity Contract [Member] \| Designated as Hedging Instrument [Member] \| Derivative Assets, Non-current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,619	4,766	338
Derivative Asset, Fair Value, Gross Liability	0	0	0
Commodity Contract [Member] \| Designated as Hedging Instrument [Member] \| Derivative Liabilities, Current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	493	185	3,702
Commodity Contract [Member] \| Designated as Hedging Instrument [Member] \| Derivative Liabilities, Non-current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	117	288	2,348
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Derivative Assets, Current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0	1,737
Derivative Asset, Fair Value, Gross Liability	0	0	0
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Derivative Assets, Non-current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0	0
Derivative Asset, Fair Value, Gross Liability	0	0	0
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Derivative Liabilities, Current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	5,156	8,032	0
Commodity Contract [Member] \| Not Designated as Hedging Instrument [Member] \| Derivative Liabilities, Non-current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	11,025	8,882	3,384
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member] \| Derivative Liabilities, Current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	3,289	3,340	3,480
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member] \| Derivative Liabilities, Non-current [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	$ 1,433	$ 2,680	$ 4,251

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

Jun. 30, 2015

Dec. 31, 2014

Jun. 30, 2014

Dec. 31, 2013

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

Cash and cash equivalents

$ 87,210

$ 21,218

$ 14,697

$ 7,841

Restricted cash and equivalents

2,316

2,056

Notes payable

105,760

75,000

132,700

Carrying Amount [Member]

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

Cash and cash equivalents

87,210

21,218

14,697

Restricted cash and equivalents

2,316

2,056

Notes payable

105,760

75,000

132,700

Long-term debt, including current maturities

1,567,727

1,542,589

1,396,950

Fair Value [Member]

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

Cash and cash equivalents, Fair Value

^[1]

87,210

21,218

14,697

Restricted Cash Fair Value Disclosure

^[1]

2,316

2,056

Notes payable, Fair Value

^[1]

105,760

75,000

132,700

Long-term debt, including current maturities, Fair Value

^[2]

$ 1,700,487

$ 1,734,555

$ 1,578,756

[1]	Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy.
[2]	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.

Other Comprehensive Income (Loss): Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 19,545	$ 17,886	$ 39,455	$ 35,746
Revenue	272,254	283,237	714,241	743,406
Utilities - Operating and maintenance	67,264	66,074	138,348	137,301
Non-regulated energy operations and maintenance	23,146	21,350	45,196	43,682
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	(56,942)	31,306	(5,083)	105,624
Income tax benefit (expense)	20,317	(10,959)	2,605	(36,632)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	(1,996)	2,177	(4,491)	3,382
Income tax benefit (expense)	735	(774)	1,989	(1,199)
Net income (loss) available for common stock	(1,261)	1,403	(2,502)	2,183
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member] \| Interest Rate Contract [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	1,670	926	3,107	1,820
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member] \| Commodity Contract [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Revenue	(3,666)	1,251	(7,598)	1,562
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Utilities - Operating and maintenance	(26)	(25)	(53)	(51)
Non-regulated energy operations and maintenance	(29)	(84)	(57)	(71)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Utilities - Operating and maintenance	454	158	908	315
Non-regulated energy operations and maintenance	251	101	502	186
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	650	150	1,300	379
Income tax benefit (expense)	(228)	(52)	(456)	(133)
Net income (loss) available for common stock	$ 422	$ 98	$ 844	$ 246

Other Comprehensive Income (Loss): Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (14,054)	$ (15,044)	$ (18,589)	$ (17,422)	$ (15,044)	$ (17,422)
Other comprehensive income (loss), net of tax	(2,805)	990	(852)	(1,167)	(1,815)	(2,019)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(16,859)	(14,054)	(19,441)	(18,589)	(16,859)	(19,441)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	5,688	5,093	(8,611)	(7,133)	5,093	(7,133)
Other comprehensive income (loss), net of tax	422	595	(556)	(1,478)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	6,110	5,688	(9,167)	(8,611)	6,110	(9,167)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(19,742)	(20,137)	(9,978)	(10,289)	(20,137)	(10,289)
Other comprehensive income (loss), net of tax	(3,227)	395	(296)	311
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	$ (22,969)	$ (19,742)	$ (10,274)	$ (9,978)	$ (22,969)	$ (10,274)

- Definition

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.

+ References + Details

Supplemental Disclosure of Cash Flow Information: Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Non-cash Investing and Financing Activities from Continuing Operations [Abstract]
Property, plant and equipment acquired with accrued liabilities	$ 36,661	$ 40,611
Increase (decrease) in capitalized assets associated with asset retirement obligations	0	(2,785)
Supplemental Cash Flow Elements [Abstract]
Interest (net of amounts capitalized)	(37,698)	(35,009)
Income taxes, net	$ (1,202)	$ (396)

Employee Benefit Plans: Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 1,494	$ 1,362	$ 2,988	$ 2,724
Interest cost	3,880	3,963	7,760	7,926
Expected return on plan assets	(4,867)	(4,516)	(9,734)	(9,032)
Prior service cost (benefit)	15	16	30	32
Net loss (gain)	2,759	1,201	5,518	2,403
Net periodic benefit cost	3,281	2,026	6,562	4,053
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	0		0
Estimated Future Employer Contributions in Current Fiscal Year			10,200
Estimated Future Employer Contributions in Next Fiscal Year			10,200
Defined Benefit Postretirement Healthcare Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	464	425	928	850
Interest cost	450	480	900	959
Expected return on plan assets	(33)	(21)	(66)	(42)
Prior service cost (benefit)	(107)	(107)	(214)	(214)
Net loss (gain)	102	40	204	80
Net periodic benefit cost	876	817	1,752	1,633
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	939		1,878
Estimated Future Employer Contributions in Current Fiscal Year			1,877
Estimated Future Employer Contributions in Next Fiscal Year			4,026
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	392	374	883	749
Interest cost	364	362	728	724
Prior service cost (benefit)	1	1	2	1
Net loss (gain)	270	124	540	249
Net periodic benefit cost	1,027	$ 861	2,153	$ 1,723
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	$ 372		744
Estimated Future Employer Contributions in Current Fiscal Year			743
Estimated Future Employer Contributions in Next Fiscal Year			$ 1,544

Commitments and Contingencies: Commitments and Contingencies - Oil Creek Fire (Details) - Pending Litigation [Member] - Oil Creek Fire [Member] - Loss from Catastrophes [Member] $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)
Minimum [Member]
Loss Contingencies [Line Items]
Insurance Coverage Deductible Per Occurrence	$ 1.0
Maximum [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 55.0

Commitments and Contingencies: Commitments and Contingencies - Dividend Restrictions (Details) $ in Millions	Jun. 30, 2015 USD ($)
Utilities Group [Member]
Related Party Transaction [Line Items]
Restricted Net Assets for Subsidiaries	$ 325

Impairment of Assets: Impairment of Long-lived assets (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 $ / bbl $ / MMcf	Mar. 31, 2015 $ / bbl $ / MMcf
Impairment of Oil and Gas Properties \| $			$ 121,690	$ 0
Oil and Gas [Member]
Impairment of Oil and Gas Properties \| $	$ 94,000	$ 22,000	$ 117,000
Average Natural Gas Price Per MCF, NYMEX					3.39	3.88
Average Natural Gas Price Per MCF, Wellhead \| $ / MMcf					2.14	2.69
Average Crude Oil Price, Per Barrel, NYMEX					71.68	82.72
Average Crude Oil Price Per Barrel, Wellhead					63.76	74.13

Impairment of Assets: Equity investments in unconsolidated subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Non-cash impairment of our Oil and Gas equity investments	$ 5,170	$ 0	$ 5,170	$ 0
Oil and Gas [Member]
Non-cash impairment of our Oil and Gas equity investments			$ 5,170
Willow Creek / Lodge Creek Pipeline and Gathering System [Member] \| Oil and Gas [Member]
Equity Method Investment, Ownership Percentage	25.00%		25.00%