0001130464-19-000035 | 10-Q | XBRL Viewer

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Document and Entity Information Document - shares	6 Months Ended
Document and Entity Information Document - shares	Jun. 30, 2019	Jul. 31, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
Document Transition Report	false
Entity File Number	001-31303
Entity Registrant Name	Black Hills Corporation
Entity Incorporation, State or Country Code	SD
Entity Tax Identification Number	46-0458824
Entity Address, Address Line One	7001 Mount Rushmore Road
Entity Address, City or Town	Rapid City
Entity Address, State or Province	SD
Entity Address, Postal Zip Code	57702
City Area Code	(605)
Local Phone Number	721-1700
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common stock of $1.00 par value
Trading Symbol	BKH
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		61,063,230
Entity Central Index Key	0001130464
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31

Condensed Consolidated Statements of Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 333,888	$ 355,704	$ 931,698	$ 931,093
Operating expenses:
Fuel, purchased power and cost of natural gas sold	89,826	104,661	338,605	352,300
Operations and maintenance	124,931	118,282	248,844	234,378
Depreciation, depletion and amortization	51,595	48,709	102,623	97,299
Taxes - property and production	13,142	13,976	26,661	27,276
Other operating expenses	393	525	833	2,015
Total operating expenses	279,887	286,153	717,566	713,268
Operating income	54,001	69,551	214,132	217,825
Interest charges -
Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts)	(36,058)	(35,365)	(72,032)	(70,803)
Allowance for funds used during construction - borrowed	1,397	511	2,355	644
Interest income	396	320	695	630
Allowance for funds used during construction - equity	127	242	175	310
Other income (expense), net	137	(1,551)	(700)	(1,723)
Total other income (expense)	(34,001)	(35,843)	(69,507)	(70,942)
Income before income taxes	20,000	33,708	144,625	146,883
Income tax benefit (expense)	(2,307)	(6,541)	(19,570)	19,261
Income from continuing operations	17,693	27,167	125,055	166,144
Net (loss) from discontinued operations	0	(2,427)	0	(4,770)
Net income	17,693	24,740	125,055	161,374
Net income attributable to noncontrolling interest	(3,110)	(2,823)	(6,664)	(6,453)
Net Income (Loss) Attributable to Parent	14,583	21,917	118,391	154,921
Net income from continuing operations	$ 14,583	$ 24,344	$ 118,391	$ 159,691
Earnings Per Share, Basic [Abstract]
Income from continuing operations, Basic (usd per share)	$ 0.24	$ 0.46	$ 1.97	$ 2.99
(Loss) from discontinued operations, Basic (usd per share)	0	(0.05)	0	(0.09)
Earnings (loss) per share, Basic (usd per share)	0.24	0.41	1.97	2.90
Earnings Per Share, Diluted [Abstract]
Income from continuing operations, Diluted (usd per share)	0.24	0.45	1.96	2.94
(Loss) from discontinued operations, Diluted (usd per share)	0	(0.05)	0	(0.09)
Earnings (loss) per share, Diluted (usd per share)	$ 0.24	$ 0.40	$ 1.96	$ 2.85
Weighted Average Number of Shares Outstanding, Basic and Diluted [Abstract]
Basic (in shares)	60,467	53,355	60,195	53,337
Diluted (in shares)	60,606	54,520	60,333	54,361

Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net income	$ 17,693	$ 24,740	$ 125,055	$ 161,374
Other comprehensive income (loss), net of tax:
Reclassification adjustments of benefit plan liability - prior service cost	(15)	(35)	(29)	(70)
Reclassification adjustments of benefit plan liability - net gain (loss)	169	487	336	973
Other comprehensive income, net of tax	232	1,161	689	2,421
Comprehensive income	17,925	25,901	125,744	163,795
Less: comprehensive income attributable to noncontrolling interest	(3,110)	(2,823)	(6,664)	(6,453)
Comprehensive income available for common stock	14,815	23,078	119,080	157,342
Interest rate swaps
Other comprehensive income (loss), net of tax:
Reclassification of net realized (gains) losses	541	561	1,091	1,122
Commodity Contract
Other comprehensive income (loss), net of tax:
Reclassification of net realized (gains) losses	(64)	118	(490)	594
Net unrealized gains (losses)	$ (399)	$ 30	$ (219)	$ (198)

Condensed Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification adjustment of benefit plan - prior service cost, (tax) benefit	$ 5	$ 9	$ 10	$ 19
Reclassification adjustment of benefit plan liabilities, (tax) benefit	(52)	(135)	(105)	(271)
Interest rate swaps
Reclassification of net realized gains/losses, (tax) benefit	(172)	(152)	(335)	(304)
Commodity Contract
Net unrealized gains/losses, (tax) benefit	119	(18)	65	51
Reclassification of net realized gains/losses, (tax) benefit	$ 19	$ (45)	$ 147	$ (190)

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 6,642	$ 20,776
Restricted cash	3,602	3,369
Accounts receivable, net	166,513	269,153
Materials, supplies and fuel	102,830	117,299
Derivative assets, current	405	1,500
Income tax receivable, net	13,547	12,978
Regulatory assets, current	48,925	48,776
Other current assets	27,209	29,982
Total current assets	369,673	503,833
Investments	41,271	41,013
Property, plant and equipment	6,317,112	6,000,015
Less: accumulated depreciation and depletion	(1,224,600)	(1,145,136)
Total property, plant and equipment, net	5,092,512	4,854,879
Other assets:
Goodwill	1,299,454	1,299,454
Intangible assets, net	13,867	14,337
Regulatory assets, non-current	234,124	235,459
Other assets, non-current	30,552	14,352
Total other assets, non-current	1,577,997	1,563,602
TOTAL ASSETS	7,081,453	6,963,327
Current liabilities:
Accounts payable	150,508	210,609
Accrued liabilities	188,517	215,501
Derivative liabilities, current	1,491	947
Regulatory liabilities, current	39,642	29,810
Notes payable	102,500	185,620
Current maturities of long-term debt	5,743	5,743
Total current liabilities	488,401	648,230
Long-term debt	3,049,672	2,950,835
Deferred credits and other liabilities:
Deferred income tax liabilities, net	343,207	311,331
Regulatory liabilities, non-current	514,914	510,984
Benefit plan liabilities	146,648	145,147
Other deferred credits and other liabilities	118,613	109,377
Total deferred credits and other liabilities	1,123,382	1,076,839
Commitments and contingencies (See Notes 8, 10, 15, 16)
Equity:
Common stock $1 par value; 100,000,000 shares authorized; issued 61,091,385 and 60,048,567 shares, respectively	61,091	60,049
Additional paid-in capital	1,522,208	1,450,569
Retained earnings	761,222	700,396
Treasury stock, at cost – 25,359 and 44,253 shares, respectively	(1,544)	(2,510)
Accumulated other comprehensive income (loss)	(26,227)	(26,916)
Total stockholders’ equity	2,316,750	2,181,588
Noncontrolling interest	103,248	105,835
Total equity	2,419,998	2,287,423
TOTAL LIABILITIES AND TOTAL EQUITY	$ 7,081,453	$ 6,963,327

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common Stock, Par Value (usd per share)	$ 1	$ 1
Common Stock, Shares Issued	61,091,385	60,048,567
Treasury Stock, Shares	25,359	44,253
Common Stock, Shares Authorized	100,000,000	100,000,000

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities:
Net income	$ 125,055	$ 161,374
Loss from discontinued operations, net of tax	0	4,770
Income from continuing operations	125,055	166,144
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	102,623	97,299
Deferred financing cost amortization	4,219	3,694
Stock compensation	7,093	5,221
Deferred income taxes	21,935	(21,419)
Employee benefit plans	5,683	6,911
Other adjustments, net	8,991	4,884
Changes in certain operating assets and liabilities:
Materials, supplies and fuel	14,911	18,492
Accounts receivable, unbilled revenues and other operating assets	99,925	50,711
Accounts payable and other operating liabilities	(107,563)	(96,394)
Regulatory assets - current	16,116	55,637
Regulatory liabilities - current	(6,348)	19,990
Other operating activities, net	(2,861)	(1,372)
Net cash provided by operating activities of continuing operations	289,779	309,798
Net cash provided by operating activities of discontinued operations	0	903
Net cash provided by operating activities	289,779	310,701
Investing activities:
Property, plant and equipment additions	(317,686)	(156,748)
Purchase of investment	0	(24,429)
Other investing activities	389	(373)
Net cash provided by (used in) investing activities of continuing operations	(317,297)	(181,550)
Net cash provided by investing activities of discontinued operations	0	18,024
Net cash provided by (used in) investing activities	(317,297)	(163,526)
Financing activities:
Dividends paid on common stock	(60,952)	(50,879)
Common stock issued	71,759	1,074
Net (payments) borrowings of short-term debt	(83,120)	(89,500)
Long-term debt - repayments	400,000	0
Long-term debt - repayments	(302,871)	(2,871)
Distributions to noncontrolling interest	(9,251)	(9,998)
Other financing activities	(1,948)	(1,527)
Net cash provided by (used in) financing activities	13,617	(153,701)
Net change in cash, cash equivalents and restricted cash	(13,901)	(6,526)
Cash, cash equivalents and restricted cash at beginning of period	24,145	18,240
Cash, cash equivalents and restricted cash at end of period	$ 10,244	$ 11,714

Condensed Consolidated Statements Of Equity (unaudited) Condensed Consolidated Statements Of Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (loss)	Noncontrolling Interest
Common Stock, Shares, Outstanding at Dec. 31, 2017		53,579,986	39,064
Total equity at Dec. 31, 2017	$ 1,820,206	$ 53,580	$ (2,306)	$ 1,150,285	$ 548,617	$ (41,202)	$ 111,232
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	136,634				133,004		3,630
Other comprehensive income (loss), net of tax	1,260					1,260
Dividends on Common Stock	(25,444)				(25,444)
Share-based compensation, shares		64,770	14,895
Share-based compensation	755	$ 65	$ (743)	1,433
Dividend reinvestment and stock purchase plan, shares		4,061
Dividend reinvestment and stock purchase plan	219	$ 4		215
Other stock transactions	2				(16)	18
Distributions to noncontrolling interest	(5,648)						(5,648)
Common Stock, Shares, Outstanding at Mar. 31, 2018		53,648,817	53,959
Total equity at Mar. 31, 2018	1,927,984	$ 53,649	$ (3,049)	1,151,933	656,161	(39,924)	109,214
Common Stock, Shares, Outstanding at Dec. 31, 2017		53,579,986	39,064
Total equity at Dec. 31, 2017	1,820,206	$ 53,580	$ (2,306)	1,150,285	548,617	(41,202)	111,232
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss), net of tax	2,421
Common Stock, Shares, Outstanding at Jun. 30, 2018		53,661,850	64,981
Total equity at Jun. 30, 2018	1,926,533	$ 53,662	$ (3,642)	1,154,947	652,642	(38,763)	107,687
Common Stock, Shares, Outstanding at Mar. 31, 2018		53,648,817	53,959
Total equity at Mar. 31, 2018	1,927,984	$ 53,649	$ (3,049)	1,151,933	656,161	(39,924)	109,214
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	24,740				21,917		2,823
Other comprehensive income (loss), net of tax	1,161					1,161
Dividends on Common Stock	(25,435)				(25,435)
Share-based compensation, shares		13,033	11,022
Share-based compensation	2,439	$ 13	$ (593)	3,019
Other stock transactions	(6)			(5)	(1)
Distributions to noncontrolling interest	(4,350)						(4,350)
Common Stock, Shares, Outstanding at Jun. 30, 2018		53,661,850	64,981
Total equity at Jun. 30, 2018	1,926,533	$ 53,662	$ (3,642)	1,154,947	652,642	(38,763)	107,687
Common Stock, Shares, Outstanding at Dec. 31, 2018		60,048,567	44,253
Total equity at Dec. 31, 2018	2,287,423	$ 60,049	$ (2,510)	1,450,569	700,396	(26,916)	105,835
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	107,362				103,808		3,554
Other comprehensive income (loss), net of tax	457					457
Dividends on Common Stock	(30,332)				(30,332)
Share-based compensation, shares		48,956	(20,497)
Share-based compensation	538	$ 49	$ 1,078	(589)
Issuance of common stock, shares		280,497
Issuance of common stock	19,999	$ 280		19,719
Issuance costs	(289)			(289)
Distributions to noncontrolling interest	(4,846)						(4,846)
Common Stock, Shares, Outstanding at Mar. 31, 2019		60,378,020	23,756
Total equity at Mar. 31, 2019	2,383,702	$ 60,378	$ (1,432)	1,469,410	777,262	(26,459)	104,543
Common Stock, Shares, Outstanding at Dec. 31, 2018		60,048,567	44,253
Total equity at Dec. 31, 2018	2,287,423	$ 60,049	$ (2,510)	1,450,569	700,396	(26,916)	105,835
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss), net of tax	689
Common Stock, Shares, Outstanding at Jun. 30, 2019		61,091,385	25,359
Total equity at Jun. 30, 2019	2,419,998	$ 61,091	$ (1,544)	1,522,208	761,222	(26,227)	103,248
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Implementation of ASU 2016-02 Leases	3,390				3,390
Common Stock, Shares, Outstanding at Mar. 31, 2019		60,378,020	23,756
Total equity at Mar. 31, 2019	2,383,702	$ 60,378	$ (1,432)	1,469,410	777,262	(26,459)	104,543
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	17,693				14,583		3,110
Other comprehensive income (loss), net of tax	232					232
Dividends on Common Stock	(30,620)				(30,620)
Share-based compensation, shares		54,767	1,603
Share-based compensation	3,890	$ 54	$ (112)	3,948
Issuance of common stock, shares		658,598
Issuance of common stock	50,001	$ 659		49,342
Issuance costs	(492)			(492)
Distributions to noncontrolling interest	(4,405)						(4,405)
Common Stock, Shares, Outstanding at Jun. 30, 2019		61,091,385	25,359
Total equity at Jun. 30, 2019	2,419,998	$ 61,091	$ (1,544)	$ 1,522,208	761,222	$ (26,227)	$ 103,248
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Implementation of ASU 2016-02 Leases	$ (3)				$ (3)

Condensed Consolidated Statements Of Equity (unaudited) Condensed Consolidated Statements of Equity (unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.505	$ 0.505	$ 0.475	$ 0.475

Management's Statement:	6 Months Ended
Management's Statement:	Jun. 30, 2019
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 2018 Annual Report on Form 10-K filed with the SEC. Segment Reporting We conduct our operations through the following reportable segments: Electric Utilities, Gas Utilities, Power Generation and Mining. Our reportable segments are based on our method of internal reporting, which is generally segregated by differences in products, services and regulation. All of our operations and assets are located within the United States. Effective January 1, 2019, we changed our measure of segment performance to adjusted operating income, which impacted our segment disclosures for all periods presented. See Note 3 for more information. On November 1, 2017, the BHC board of directors approved a complete divestiture of our Oil and Gas segment. We completed the divestiture in 2018. The Oil and Gas segment assets and liabilities were classified as held for sale and the results of operations were shown in income (loss) from discontinued operations, except for certain general and administrative costs and interest expense which do not meet the criteria for income (loss) from discontinued operations. At the time the assets were classified as held for sale, depreciation, depletion and amortization expenses were no longer recorded. Unless otherwise noted, the amounts presented in the accompanying notes to the Condensed Consolidated Financial Statements relate to the Company’s continuing operations. See Note 17 for more information on discontinued operations. Use of Estimates and Basis of Presentation The information furnished in the accompanying Condensed Consolidated Financial Statements reflects certain estimates required and all adjustments, including accruals, which are, in the opinion of management, necessary for a fair presentation of the June 30, 2019 and December 31, 2018 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. 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, 2019 and June 30, 2018, and our financial condition as of June 30, 2019 and December 31, 2018 are not necessarily indicative of the results of operations and financial condition to be expected for any other period. All earnings per share amounts discussed refer to diluted earnings per share unless otherwise noted. Recently Issued Accounting Standards Simplifying the Test for Goodwill Impairment, 2017-04 In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment by eliminating step 2 from the goodwill impairment test. Under the new guidance, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss will be recognized in an amount equal to that excess, limited to the amount of goodwill allocated to that reporting unit. The new standard is effective for interim and annual reporting periods beginning after December 1, 2019, applied on a prospective basis with early adoption permitted. We do not anticipate the adoption of this guidance to have any impact on our financial position, results of operations or cash flows. Financial Instruments -- Credit Losses: Measurement of Credit Losses on Financial Instruments, ASU 2018-19 In June 2016, the FASB issued ASU 2016-13, Financial Instruments -- Credit Losses: Measurement of Credit Losses on Financial Instruments, which was subsequently amended by ASU 2018-19 in November 2018. The standard introduces new accounting guidance for credit losses on financial instruments within its scope, including trade receivables. This new guidance adds an impairment model that is based on expected losses rather than incurred losses. It is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We are currently assessing the impacts of adopting this standard. Recently Adopted Accounting Standards Leases, ASU 2016-02 In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) to increase transparency and comparability among organizations by requiring the recognition of right-of-use assets and lease liabilities on the balance sheet for most leases, whereas previously only financing-type lease liabilities (capital leases) were recognized on the balance sheet. Under the new standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. We adopted the standard effective January 1, 2019. We elected not to recast comparative periods coinciding with the new lease standard transition and will report these comparative periods as presented under previous lease guidance. In addition, we elected the package of practical expedients permitted under the transition guidance with the new standard, which among other things, allowed us to carry forward the historical lease classification. We also elected the practical expedient related to land easements, allowing us to carry forward our accounting treatment for existing land easement agreements. Adoption of the new standard resulted in the recording of an operating lease right-of-use asset of $3.1 million, an operating lease obligation liability of $3.2 million, and an accrued rent receivable of $4.5 million, as of January 1, 2019. The cumulative effect of the adoption, net of tax impact, was $3.4 million, which was recorded as an adjustment to retained earnings. Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities, ASU 2017-12 Effective January 1, 2019, we adopted ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. This standard better aligns risk management activities and financial reporting for hedging relationships, simplifies hedge accounting requirements and improves disclosures of hedging arrangements. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows.

Revenue:

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

Revenue

REVENUE

Revenue Recognition

As of January 1, 2018, we adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606), and its related amendments (collectively known as ASC 606). Revenue is recognized in an amount that reflects the consideration we expect to receive in exchange for goods or services, when control of the promised goods or services is transferred to our customers. The following tables depict the disaggregation of revenue, including intercompany revenue, from contracts with customers by customer type and timing of revenue recognition for each of the reporting segments, for the three and six months ended June 30, 2019 and 2018. Sales tax and other similar taxes are excluded from revenues.



Three Months Ended June 30, 2019	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues			Total
Customer types:	(in thousands)
Retail	$	139,732	$	123,630	$	—	$	12,428	$	(7,041	)	$	268,749
Transportation	—		28,623		—		—		(276		)	28,347
Wholesale	6,781		—		15,062		—		(13,296		)	8,547
Market - off-system sales	3,448		161		—		—		(1,335		)	2,274
Transmission/Other	14,416		11,612		—		—		(4,199		)	21,829
Revenue from contracts with customers	$	164,377	$	164,026	$	15,062	$	12,428	$	(26,147	)	$	329,746
Other revenues	1,977		1,443		9,646		617		(9,541		)	4,142
Total revenues	$	166,354	$	165,469	$	24,708	$	13,045	$	(35,688	)	$	333,888

Timing of revenue recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	12,428	$	(7,041	)	$	5,387
Services transferred over time	164,377		164,026		15,062		—		(19,106		)	324,359
Revenue from contracts with customers	$	164,377	$	164,026	$	15,062	$	12,428	$	(26,147	)	$	329,746



Three Months Ended June 30, 2018	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues			Total
Customer Types:
Retail	$	145,377	$	135,863	$	—	$	16,345	$	(7,979	)	$	289,606
Transportation	—		29,011		—		—		(301		)	28,710
Wholesale	8,191		—		13,603		—		(12,473		)	9,321
Market - Off-System Sales	4,938		162		—		—		(1,660		)	3,440
Transmission/Other	13,356		11,672		—		—		(3,644		)	21,384
Revenue from contracts with customers	$	171,862	$	176,708	$	13,603	$	16,345	$	(26,057	)	$	352,461
Other Revenues	1,754		912		9,141		554		(9,118		)	3,243
Total Revenues	$	173,616	$	177,620	$	22,744	$	16,899	$	(35,175	)	$	355,704

Timing of Revenue Recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	16,345	$	(7,978	)	$	8,367
Services transferred over time	171,862		176,708		13,603		—		(18,079		)	344,094
Revenue from Contracts with Customers	$	171,862	$	176,708	$	13,603	$	16,345	$	(26,057	)	$	352,461



Six Months Ended June 30, 2019	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer types:	(in thousands)
Retail	$	293,195	$	477,905	$	—	$	28,257	$	(15,169	)	$	784,188
Transportation	—		73,140		—		—		(708		)	72,432
Wholesale	15,124		—		30,531		—		(26,509		)	19,146
Market - off-system sales	10,140		378		—		—		(3,559		)	6,959
Transmission/Other	28,591		24,802		—		—		(8,402		)	44,991
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716
Other revenues	2,231		324		19,422		1,217		(19,212		)	3,982
Total revenues	$	349,281	$	576,549	$	49,953	$	29,474	$	(73,559	)	$	931,698

Timing of revenue recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	28,257	$	(15,169	)	$	13,088
Services transferred over time	347,050		576,225		30,531		—		(39,178		)	914,628
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716



Six Months Ended June 30, 2018	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer Types:
Retail	$	292,434	$	477,257	$	—	$	32,902	$	(15,821	)	$	786,772
Transportation	—		70,681		—		—		(710		)	69,971
Wholesale	17,241		—		28,371		—		(25,521		)	20,091
Market - Off-System Sales	9,082		589		—		—		(4,182		)	5,489
Transmission/Other	26,427		24,341		—		—		(7,275		)	43,493
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816
Other Revenues	1,987		2,096		18,311		1,125		(18,242		)	5,277
Total Revenues	$	347,171	$	574,964	$	46,682	$	34,027	$	(71,751	)	$	931,093

Timing of Revenue Recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	32,902	$	(15,820	)	$	17,082
Services transferred over time	345,184		572,868		28,371		—		(37,689		)	908,734
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816

(a)

Due to the changes in our segment disclosures discussed in Note 3, Power Generation Wholesale revenue was revised for the three and six months ended June 30, 2018, which resulted in an increase of $0.9 million and $1.7 million, respectively. The changes to Power Generation Wholesale revenue were offset by changes to eliminations in Inter-company Revenues within Corporate and Other and there was no impact to our consolidated Total Revenues.

Contract Balances

The nature of our primary revenue contracts provides an unconditional right to consideration upon service delivery; therefore, no customer contract assets or liabilities exist. The unconditional right to consideration is represented by the balance in our Accounts Receivable further discussed in Note 4. We do not typically incur costs that would be capitalized to obtain or fulfill a revenue contract.

Business Segment Information:

6 Months Ended

Jun. 30, 2019

Segment Reporting Information, Additional Information [Abstract]

Business Segment Information

BUSINESS SEGMENT INFORMATION

Our reportable segments are based on our method of internal reporting, which is generally segregated by differences in products, services and regulation.

Accounting standards for presentation of segments requires an approach based on the way we organize the segments for making operating decisions and how the chief operating decision maker (CODM) assesses performance. Effective January 1, 2019, we concluded that adjusted operating income, instead of net income available for common stock which was used previously, is the most relevant metric for measuring segment performance. The change to our segment performance measure resulted in a revision of the Company’s segment disclosures for all periods to report adjusted operating income as the measure of segment performance.

Prior to January 1, 2019, operating income for the Electric Utilities and Power Generation segments and Corporate and Other included the impacts of finance lease accounting relating to Colorado Electric’s PPA with Colorado IPP. This PPA provides 200 MW of energy and capacity to Colorado Electric from Colorado IPP’s combined-cycle turbines and expires on December 31, 2031. Finance lease accounting required us to de-recognize the asset from Colorado IPP (Power Generation segment), which legally owns the asset, and recognize it at Colorado Electric (Electric Utilities segment).

The CODM assesses the performance of our segments by using adjusted operating income, which recognizes intersegment revenues, costs, and assets for Colorado Electric’s PPA with Colorado IPP on an accrual basis rather than as a finance lease. Effective January 1, 2019, we changed how we account for this PPA at the segment level, which impacts disclosures for all periods for revenues, fuel and purchased power cost, operating income and total assets for the Electric Utilities and Power Generation segments as well as Corporate and Other. There were no adjustments to Gas Utilities and Mining segments and this change had no effect on our consolidated revenues, fuel and purchased power cost, operating income or total assets.

Segment information and Corporate and Other is as follows (in thousands):




Three Months Ended June 30, 2019	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	159,140	$	1,977	$	5,237		$	—		$	166,354
Gas Utilities	163,303		1,443		723			—			165,469
Power Generation ^(a)	1,765		434		13,297			9,212			24,708
Mining	5,538		288		6,890			329			13,045
Inter-company eliminations ^(a)	—		—		(26,147		)	(9,541		)	(35,688		)
Total	$	329,746	$	4,142	$	—		$	—		$	333,888




Three Months Ended June 30, 2018	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	166,565	$	1,754	$	5,297		$	—		$	173,616
Gas Utilities	176,399		912		309			—			177,620
Power Generation ^(a)	1,130		348		12,473			8,793			22,744
Mining	8,367		229		7,978			325			16,899
Inter-company eliminations ^(a)	—		—		(26,057		)	(9,118		)	(35,175		)
Total	$	352,461	$	3,243	$	—		$	—		$	355,704



Six Months Ended June 30, 2019	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
Six Months Ended June 30, 2019	Contract Customers		Other Revenues		Contract Customers			Other Revenues			Total Revenues
Segment:
Electric Utilities	$	335,803	$	2,231	$	11,247		$	—		$	349,281
Gas Utilities	574,803		324		1,422			—			576,549
Power Generation ^(a)	4,022		870		26,509			18,552			49,953
Mining	13,088		557		15,169			660			29,474
Inter-company eliminations ^(a)	—		—		(54,347		)	(19,212		)	(73,559		)
Total	$	927,716	$	3,982	$	—		$	—		$	931,698




Six Months Ended June 30, 2018	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	333,743	$	1,987	$	11,441		$	—		$	347,171
Gas Utilities	572,141		2,096		727			—			574,964
Power Generation ^(a)	2,850		718		25,521			17,593			46,682
Mining	17,082		476		15,820			649			34,027
Inter-company eliminations ^(a)	—		—		(53,509		)	(18,242		)	(71,751		)
Total	$	925,816	$	5,277	$	—		$	—		$	931,093

(a)

Due to the changes in our segment disclosures, Power Generation Inter-company Operating Revenue for Contract Customers was revised for the three and six months ended June 30, 2018 which resulted in an increase of $0.9 million and $1.7 million, respectively. The changes to Power Generation were offset by changes to Inter-company eliminations within Corporate and Other and there was no impact on our consolidated Total revenues.




	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Adjusted operating income:
Electric Utilities ^(a)	$	33,546		$	41,200		$	74,566		$	79,680
Gas Utilities	8,557			16,485			111,871			111,928
Power Generation ^(a)	10,156			8,877			22,123			20,652
Mining	1,640			3,825			5,977			8,096
Corporate and Other ^(a)	102			(836		)	(405		)	(2,531		)
Operating income	54,001			69,551			214,132			217,825

Interest expense, net	(34,265		)	(34,534		)	(68,982		)	(69,529		)
Other income (expense), net	264			(1,309		)	(525		)	(1,413		)
Income tax benefit (expense) ^(b)	(2,307		)	(6,541		)	(19,570		)	19,261
Income from continuing operations	17,693			27,167			125,055			166,144
Net (loss) from discontinued operations	—			(2,427		)	—			(4,770		)
Net income	17,693			24,740			125,055			161,374
Net income attributable to noncontrolling interest	(3,110		)	(2,823		)	(6,664		)	(6,453		)
Net income available for common stock	$	14,583		$	21,917		$	118,391		$	154,921

___________


(a)	Due to the changes in our segment disclosures, Adjusted operating income was revised for the three and six months ended June 30, 2018, which resulted in an increase (decrease) as follows (in millions):



Segment	Three Months Ended June 30, 2018			Six Months Ended June 30, 2018
Electric Utilities	$	1.6		$	3.3
Power Generation	(1.4		)	(3.0		)
Corporate and Other	(0.2		)	(0.3		)
	$	—		$	—


(b)	Income tax benefit (expense) for the six months ended June 30, 2018 included a $49 million tax benefit resulting from legal entity restructuring. See Note 18 for more information.

Segment information and Corporate and Other 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, 2019		December 31, 2018
Segment:
Electric Utilities ^(a)	$	2,777,803	$	2,707,695
Gas Utilities	3,645,840		3,623,475
Power Generation ^(a)	379,140		342,085
Mining	62,491		80,594
Corporate and Other	216,179		209,478
Total assets	$	7,081,453	$	6,963,327

___________

(a)

Due to the changes in our segment disclosures, Electric Utilities and Power Generation Total assets were revised as of December 31, 2018 which resulted in an increase (decrease) of ($188) million and $188 million, respectively. There was no impact on our consolidated Total assets.

Accounts Receivable:

6 Months Ended

Jun. 30, 2019

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, 2019	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	39,982	$	31,573	$	(526	)	$	71,029
Gas Utilities	67,686		23,753		(4,391		)	87,048
Power Generation	2,867		—		—			2,867
Mining	2,505		—		—			2,505
Corporate	3,233		—		(169		)	3,064
Total	$	116,273	$	55,326	$	(5,086	)	$	166,513



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2018	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	39,721	$	35,125	$	(448	)	$	74,398
Gas Utilities	96,123		90,521		(2,592		)	184,052
Power Generation	1,876		—		—			1,876
Mining	3,988		—		—			3,988
Corporate	5,008		—		(169		)	4,839
Total	$	146,716	$	125,646	$	(3,209	)	$	269,153

- 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, 2019

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Accounting

REGULATORY ACCOUNTING

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



	June 30, 2019			December 31, 2018
Regulatory assets
Deferred energy and fuel cost adjustments ^(a)	$	34,257		$	29,661
Deferred gas cost adjustments ^(a)	2,342			3,362
Gas price derivatives ^(a)	3,945			6,201
Deferred taxes on AFUDC^(b)	7,716			7,841
Employee benefit plans ^(c)	109,899			110,524
Environmental^(a)	931			959
Loss on reacquired debt^(a)	20,140			21,001
Renewable energy standard adjustment ^(a)	1,994			1,722
Deferred taxes on flow through accounting^(c)	36,552			31,044
Decommissioning costs ^(b)	11,518			11,700
Gas supply contract termination ^(a)	11,413			14,310
Other regulatory assets^(a)	42,342			45,910
Total regulatory assets	283,049			284,235
Less current regulatory assets	(48,925		)	(48,776		)
Regulatory assets, non-current	$	234,124		$	235,459

Regulatory liabilities
Deferred energy and gas costs^(a)	$	16,808		$	6,991
Employee benefit plan costs and related deferred taxes^(c)	41,814			42,533
Cost of removal^(a)	158,477			150,123
Excess deferred income taxes ^(c)	307,871			310,562
TCJA revenue reserve	11,436			18,032
Other regulatory liabilities^(c)	18,150			12,553
Total regulatory liabilities	554,556			540,794
Less current regulatory liabilities	(39,642		)	(29,810		)
Regulatory liabilities, non-current	$	514,914		$	510,984

__________


(a)	We are allowed 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.

Regulatory Matters

Except as discussed below, there have been no other significant changes to our Regulatory Matters from those previously disclosed in Note 13 of the Notes to the Consolidated Financial Statements in our 2018 Annual Report on Form 10-K.

Regulatory Activity

Renewable Ready Service Tariffs and Corriedale Wind Energy Project

South Dakota Electric and Wyoming Electric received approvals for the Renewable Ready Service Tariffs and related jointly-filed CPCN to construct the $57 million, 40 MW Corriedale Wind Energy Project. The wind project will be jointly owned by the two electric utilities to deliver renewable energy for large commercial and industrial customers and governmental agencies. The project is expected to be in service in 2020.

Kansas

On June 25, 2019, Kansas Gas received approval from the Kansas Corporation Commission for an annual increase in revenue of $1.4 million, effective July 1, 2019, based on updates to the Gas System Reliability Surcharge Rider.

Wyoming Gas

On June 13, 2019, we received approval from the WPSC for a request to consolidate our Wyoming gas utility operations into a new utility entity. The Wyoming portion of Black Hills Gas Distribution, LLC, Cheyenne Light’s natural gas utility operations, and Wyoming Gas (Northwest Wyoming) will be combined into a new company called Black Hills Wyoming Gas, LLC. On June 3, 2019, Wyoming Gas filed a rate review application with the WPSC to consolidate the rates, tariffs and services of its four existing gas distribution territories in Wyoming. The rate review requests $16 million in new revenue to recover investments in safety, reliability and system integrity. Wyoming Gas is also requesting a new rider mechanism to recover safety and integrity investments in its system.

Blockchain Interruptible Service Tariff

On April 30, the WPSC approved Wyoming Electric’s application for a new Blockchain Interruptible Service Tariff. The utility has partnered with the economic development organization for City of Cheyenne and Laramie County to actively recruit blockchain customers to the state. This tariff is complementary to recently enacted Wyoming legislation supporting the development of blockchain within the state.

Nebraska

On March 29, 2019, Nebraska Gas filed an application with the NPSC requesting approval to merge its two gas distribution companies in Nebraska. A rate review is expected to be filed in 2020 to consolidate the rates, tariffs and services of its two existing natural gas distribution companies.

Colorado

On February 1, 2019, Colorado Gas filed a rate review with the CPUC requesting approval to consolidate rates, tariffs, and services of its two existing gas distribution territories in Colorado. The rate review requests $2.5 million in new revenue to recover investments in safety, reliability and system integrity. Colorado Gas is also requesting a new rider mechanism to recover safety and integrity investments in its system.

Materials, Supplies and Fuel:

6 Months Ended

Jun. 30, 2019

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, 2019		December 31, 2018
Materials and supplies	$	80,639	$	75,081
Fuel - Electric Utilities	2,350		2,850
Natural gas in storage held for distribution	19,841		39,368
Total materials, supplies and fuel	$	102,830	$	117,299

Earnings Per Share:

6 Months Ended

Jun. 30, 2019

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 was as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018

Net income available for common stock	$	14,583	$	21,917	$	118,391	$	154,921

Weighted average shares - basic	60,467		53,355		60,195		53,337
Dilutive effect of:
Equity Units ^(a)	—		1,057		—		904
Equity compensation	139		108		138		120
Weighted average shares - diluted	60,606		54,520		60,333		54,361

__________


(a)	Calculated using the treasury stock method. On November 1, 2018, we completed settlement of the stock purchase contracts that were components of the Equity Units issued in November 2015.

The following outstanding securities were 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,
	2019	2018	2019	2018

Equity compensation	—	15	—	17
Anti-dilutive shares	—	15	—	17

Notes Payable, Current Maturities and Debt:

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

Notes Payable, Current Maturities and Debt

NOTES PAYABLE, CURRENT MATURITIES AND DEBT

We had the following notes payable outstanding in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	June 30, 2019				December 31, 2018
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	—	$	10,429	$	—	$	22,311
CP Program	102,500		—		185,620		—
Total	$	102,500	$	10,429	$	185,620	$	22,311

Our $750 million corporate Revolving Credit Facility extends through July 30, 2023 with two, one year extension options (subject to consent from lenders). This facility includes an accordion feature that allows us, with the consent of the administrative agent, the issuing agents and each bank increasing or providing a new commitment, to increase total commitments up to $1.0 billion. 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 Corporate credit rating from S&P, Fitch, and Moody's for our senior unsecured long-term 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, 2019. Based on our credit ratings, a 0.175% commitment fee was charged on the unused amount at June 30, 2019.

We have a $750 million, unsecured CP Program that is backstopped by the Revolving Credit Facility. Amounts outstanding under the Revolving Credit Facility and the CP Program, either individually or in the aggregate, cannot exceed $750 million. The notes issued under the CP Program may have maturities not to exceed 397 days from the date of issuance and bear interest (or are sold at par less a discount representing an interest factor) based on, among other things, the size and maturity date of the note, the frequency of the issuance and our credit ratings. Under the CP Program, any borrowings rank equally with our unsecured debt. Notes under the CP Program are not registered and are offered and issued pursuant to a registration exemption. Our net payments under the CP Program during the six months ended June 30, 2019 were $83 million. At June 30, 2019, the weighted average interest rate on CP Program borrowings was 2.60%.

Debt Covenants

Under our Revolving Credit Facility and term loan agreements, we are required to maintain a Consolidated Indebtedness to Capitalization Ratio not to exceed 0.65 to 1.00. Our Consolidated Indebtedness to Capitalization Ratio was calculated by dividing (i) Consolidated Indebtedness, which includes letters of credit and certain guarantees issued, by (ii) Capital, which includes Consolidated Indebtedness plus Net Worth, which excludes noncontrolling interest in subsidiaries. As of June 30, 2019, we were in compliance with these covenants.

Long-Term Debt

On June 17, 2019, we amended our Corporate term loan due July 30, 2020. This amendment increased total commitments to $400 million from $300 million, extended the term through June 17, 2021, and has substantially similar terms and covenants as the amended and restated Revolving Credit Facility. The net proceeds from the increase in total commitments were used to pay down short-term debt. The interest cost associated with this term loan is determined based upon our corporate credit rating from S&P, Fitch, and Moody’s for our senior unsecured long-term debt. Based on our credit ratings, the margins for base rate borrowings and Eurodollar borrowings were 0.000% and 0.700%, respectively, at June 30, 2019.

Equity:	6 Months Ended
Equity:	Jun. 30, 2019
Statement of Stockholders' Equity [Abstract]
Equity	EQUITY At-the-Market Equity Offering Program Our ATM equity offering program allows us to sell shares of our common stock with an aggregate value of up to $300 million. The shares may be offered from time to time pursuant to a sales agreement dated August 4, 2017. Shares of common stock are offered pursuant to our shelf registration statement filed with the SEC. During the three months ended June 30, 2019, we issued a total of 658,598 shares of common stock under the ATM equity offering program for proceeds of $49 million, net of $0.5 million in commissions. During the six months ended June 30, 2019, we issued a total of 939,095 shares of common stock under the ATM equity offering program for proceeds of $69 million, net of $0.7 million in commissions. As of June 30, 2019, there were no shares that were sold, but not settled.

Risk Management Activities:

6 Months Ended

Jun. 30, 2019

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 and Credit Policies and Procedures as discussed in our 2018 Annual Report on Form 10-K.

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, but not limited to, commodity price risk associated with our retail natural gas marketing activities and our fuel procurement for certain gas-fired generation assets.

Credit Risk

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

For other than retail utility 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 on 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 and Condensed Consolidated Statements of Comprehensive Income are detailed below and in Note 11.

Utilities

The operations of our utilities, including natural gas sold by our Gas Utilities and natural gas used by our Electric Utilities’ 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, over-the-counter swaps 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.

For our regulated utilities’ hedging plans, 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.

We buy, sell and deliver natural gas at competitive prices by managing commodity price risk. As a result of these activities, this area of our business is exposed to risks associated with changes in the market price of natural gas. We manage our exposure to such risks using over-the-counter and exchange traded options and swaps with counterparties in anticipation of forecasted purchases and/or sales during time frames ranging from July 2019 through May 2021; a portion of these swaps have been designated as cash flow hedges to mitigate the commodity price risk associated with forward contracts to deliver gas to our Choice Gas Program customers. The gain or loss on these designated derivatives is reported in AOCI in the accompanying Condensed Consolidated Balance Sheets. Effectiveness of our hedged position is evaluated at inception of the hedge, upon occurrence of a triggering event and as of the end of each quarter.

The contract or notional amounts and terms of the natural gas derivative commodity instruments held at our utilities are composed of both long and short positions. We were in a net long position as of:



	June 30, 2019		December 31, 2018
	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)
Natural gas futures purchased	2,480,000	18	4,000,000	24
Natural gas options purchased, net	2,160,000	9	4,320,000	13
Natural gas basis swaps purchased	2,360,000	18	3,960,000	24
Natural gas over-the-counter swaps, net ^(b)	6,020,000	23	3,660,000	24
Natural gas physical contracts, net ^(c)	1,717,075	9	18,325,852	30

__________


(a)	Term reflects the maximum forward period hedged.


(b)	As of June 30, 2019, 2,130,000 MMBtus were designated as cash flow hedges.


(c)	Volumes exclude contracts that qualify for the normal purchase, normal sales exception.

Based on June 30, 2019 prices, a $0.4 million gain would be realized, reported in pre-tax earnings and reclassified from AOCI during the next 12 months. As market prices fluctuate, estimated and actual realized gains or losses will change during future periods.

We have certain derivative contracts which contain credit provisions. These credit provisions may require the Company to post collateral when credit exposure to the Company is in excess of a negotiated line of unsecured credit. At June 30, 2019, the Company posted $0.5 million related to such provisions, which is included in Other current assets on the Condensed Consolidated Balance Sheets.

Cash Flow Hedges

The impacts of cash flow hedges on our Condensed Consolidated Statements of Income is presented below for the three and six months ended June 30, 2019 and 2018. Note that this presentation does not reflect gains or losses arising from the underlying physical transactions; therefore, it is not indicative of the economic profit or loss we realized when the underlying physical and financial transactions were settled.



Three Months Ended June 30, 2019
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(713	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	83
Total		$	(630	)



Three Months Ended June 30, 2018
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(713	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	(163		)
Total		$	(876	)



Six Months Ended June 30, 2019
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(1,426	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	637
Total		$	(789	)



Six Months Ended June 30, 2018
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(1,426	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	(784		)
Total		$	(2,210	)

The following tables summarize the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss) for the three and six months ended June 30, 2019 and 2018.




	Three Months Ended June 30,
	2019			2018
	(in thousands)
Increase (decrease) in fair value:
Forward commodity contracts	$	(518	)	$	48
Recognition of (gains) losses in earnings due to settlements:
Interest rate swaps	713			713
Forward commodity contracts	(83		)	163
Total other comprehensive income (loss) from hedging	$	112		$	924



	Six Months Ended June 30,
	2019			2018
	(in thousands)
Increase (decrease) in fair value:
Forward commodity contracts	$	(284	)	$	(249	)
Recognition of (gains) losses in earnings due to settlements:
Interest rate swaps	1,426			1,426
Forward commodity contracts	(637		)	784
Total other comprehensive income (loss) from hedging	$	505		$	1,961

Derivatives Not Designated as Hedge Instruments

The following table summarizes the impacts of derivative instruments not designated as hedge instruments on our Condensed Consolidated Statements of Income for the three and six months ended June 30, 2019 and 2018 (in thousands). Note that this presentation does not reflect gains or losses arising from the underlying physical transactions; therefore, it is not indicative of the economic profit or loss we realized when the underlying physical and financial transactions were settled.




		Three Months Ended June 30,
		2019			2018
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income			Amount of Gain/(Loss) on Derivatives Recognized in Income

Commodity derivatives	Fuel, purchased power and cost of natural gas sold	$	(1,185	)	$	771
		$	(1,185	)	$	771



		Six Months Ended June 30,
		2019			2018
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income			Amount of Gain/(Loss) on Derivatives Recognized in Income

Commodity derivatives	Fuel, purchased power and cost of natural gas sold	$	(1,160	)	$	1,025
		$	(1,160	)	$	1,025

As discussed above, financial instruments used in our regulated utilities are not designated as cash flow hedges. However, there is no earnings impact because the unrealized gains and losses arising from the use of these financial instruments are recorded as Regulatory assets or Regulatory liabilities. The net unrealized losses included in our Regulatory asset or Regulatory liability accounts related to the hedges in our utilities were $3.9 million and $6.2 million for June 30, 2019 and December 31, 2018, respectively.

Fair Value Measurements:

6 Months Ended

Jun. 30, 2019

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, 9, 10 and 11 to the Consolidated Financial Statements included in our 2018 Annual Report on Form 10-K 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

The commodity contracts for our Utilities Segments, are valued using the market approach and include exchange-traded futures, options, basis swaps and over-the-counter swaps and options (Level 2) for natural gas contracts. For exchange-traded futures, options and basis swap assets and liabilities, fair value was derived using broker quotes validated by the exchange settlement pricing for the applicable contract. For over-the-counter instruments, the fair value is obtained by utilizing a nationally recognized service that obtains observable inputs to compute the fair value, which we validate by comparing our valuation with the counterparty. The fair value of these swaps includes a CVA component based on the credit spreads of the counterparties when we are in an unrealized gain position or on our own credit spread when we are in an unrealized loss position.

Recurring Fair Value Measurements



	As of June 30, 2019
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Utilities	$	—	$	986	$	—	$	(575	)	$	411
Total	$	—	$	986	$	—	$	(575	)	$	411

Liabilities:
Commodity derivatives — Utilities	$	—	$	5,567	$	—	$	(3,945	)	$	1,622
Total	$	—	$	5,567	$	—	$	(3,945	)	$	1,622



	As of December 31, 2018
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Utilities	$	—	$	2,927	$	—	$	(1,408	)	$	1,519
Total	$	—	$	2,927	$	—	$	(1,408	)	$	1,519

Liabilities:
Commodity derivatives — Utilities	$	—	$	6,801	$	—	$	(5,794	)	$	1,007
Total	$	—	$	6,801	$	—	$	(5,794	)	$	1,007

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.

The following table presents the fair value and balance sheet classification of our derivative instruments (in thousands) as of:



	Balance Sheet Location	June 30, 2019			December 31, 2018
Derivatives designated as hedges:
Asset derivative instruments:
Current commodity derivatives	Derivative assets — current	$	—		$	415
Noncurrent commodity derivatives	Other assets, non-current	4			18
Liability derivative instruments:
Current commodity derivatives	Derivative liabilities — current	(449		)	(114		)
Noncurrent commodity derivatives	Other deferred credits and other liabilities	(58		)	(4		)
Total derivatives designated as hedges		$	(503	)	$	315

Derivatives not designated as hedges:
Asset derivative instruments:
Current commodity derivatives	Derivative assets — current	$	405		$	1,085
Noncurrent commodity derivatives	Other assets, non-current	2			1
Liability derivative instruments:
Current commodity derivatives	Derivative liabilities — current	(1,042		)	(833		)
Noncurrent commodity derivatives	Other deferred credits and other liabilities	(73		)	(56		)
Total derivatives not designated as hedges		$	(708	)	$	197

Fair value measurements also apply to the valuation of our pension and postretirement plan assets. Current accounting guidance requires employers to annually disclose information about the fair value measurements of their assets of a defined benefit pension or other postretirement plan. The fair value of these assets is presented in Note 18 to the Consolidated Financial Statements included in our 2018 Annual Report on Form 10-K.

Fair Value of Financial Instruments:

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

FAIR VALUE OF FINANCIAL INSTRUMENTS

Other financial instruments for which the carrying value did not equal fair value were as follows (in thousands) as of:



	June 30, 2019				December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current maturities ^{(a) (b)}	$	3,055,415	$	3,337,314	$	2,956,578	$	3,039,108

__________


(a)	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.

(b)

Carrying amount of long-term debt is net of deferred financing costs.

- 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, 2019

Statement of Comprehensive Income [Abstract]

Other Comprehensive Income (Loss)

OTHER COMPREHENSIVE INCOME (LOSS)

We record deferred gains (losses) in AOCI related to interest rate swaps designated as cash flow hedges, commodity contracts designated as cash flow hedges and the amortization of components of our defined benefit plans. Deferred gains (losses) for our commodity contracts designated as cash flow hedges are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate swaps are recognized in earnings as they are amortized.

The following table details reclassifications out of AOCI and into net income. The amounts in parentheses below indicate decreases to net income in the Condensed Consolidated Statements of Income for the period, net of tax (in thousands):



	Location on the Condensed Consolidated Statements of Income	Amount Reclassified from AOCI
		Three Months Ended						Six Months Ended
		June 30, 2019			June 30, 2018			June 30, 2019			June 30, 2018
Gains and (losses) on cash flow hedges:
Interest rate swaps	Interest expense	$	(713	)	$	(713	)	$	(1,426	)	$	(1,426	)
Commodity contracts	Fuel, purchased power and cost of natural gas sold	83			(163		)	637			(784		)
		(630		)	(876		)	(789		)	(2,210		)
Income tax	Income tax benefit (expense)	153			197			188			494
Total reclassification adjustments related to cash flow hedges, net of tax		$	(477	)	$	(679	)	$	(601	)	$	(1,716	)

Amortization of components of defined benefit plans:
Prior service cost	Operations and maintenance	$	20		$	44		$	39		$	89

Actuarial gain (loss)	Operations and maintenance	(221		)	(622		)	(441		)	(1,244		)
		(201		)	(578		)	(402		)	(1,155		)
Income tax	Income tax benefit (expense)	47			126			95			252
Total reclassification adjustments related to defined benefit plans, net of tax		$	(154	)	$	(452	)	$	(307	)	$	(903	)
Total reclassifications		$	(631	)	$	(1,131	)	$	(908	)	$	(2,619	)

Balances by classification included within AOCI, net of tax on the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands):



	Interest Rate Swaps			Commodity Derivatives			Employee Benefit Plans			Total
As of December 31, 2018	$	(17,307	)	$	328		$	(9,937	)	$	(26,916	)
Other comprehensive income (loss)
before reclassifications	—			(219		)	—			(219		)
Amounts reclassified from AOCI	1,091			(490		)	307			908
As of June 30, 2019	$	(16,216	)	$	(381	)	$	(9,630	)	$	(26,227	)


	Interest Rate Swaps			Commodity Derivatives			Employee Benefit Plans			Total
Balance as of December 31, 2017	$	(19,581	)	$	(518	)	$	(21,103	)	$	(41,202	)
Other comprehensive income (loss)
before reclassifications	—			(198		)	—			(198		)
Amounts reclassified from AOCI	1,122			594			903			2,619
Reclassifications of certain tax effects from AOCI	15			—			3			18
As of June 30, 2018	$	(18,444	)	$	(122	)	$	(20,197	)	$	(38,763	)

Supplemental Disclosure of Cash Flow Information:

6 Months Ended

Jun. 30, 2019

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information

SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION



Six Months Ended	June 30, 2019			June 30, 2018
	(in thousands)
Non-cash investing and financing activities —
Property, plant and equipment acquired with accrued liabilities	$	83,486		$	37,168

Cash (paid) refunded during the period —
Interest (net of amounts capitalized)	$	(67,624	)	$	(67,119	)
Income taxes	$	1,790		$	(14,837	)

Employee Benefit Plans:

6 Months Ended

Jun. 30, 2019

Defined Benefit Plan [Abstract]

Employee Benefit Plans

EMPLOYEE BENEFIT PLANS

Defined Benefit Pension Plan

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Service cost	$	1,345		$	1,709		$	2,691		$	3,417
Interest cost	4,344			3,868			8,687			7,735
Expected return on plan assets	(6,100		)	(6,185		)	(12,200		)	(12,370		)
Prior service cost	7			14			13			29
Net loss (gain)	940			2,157			1,881			4,315
Net periodic benefit cost	$	536		$	1,563		$	1,072		$	3,126

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,
	2019			2018			2019			2018
Service cost	$	454		$	572		$	908		$	1,145
Interest cost	563			521			1,123			1,042
Expected return on plan assets	(58		)	(56		)	(115		)	(113		)
Prior service cost (benefit)	(100		)	(99		)	(199		)	(198		)
Net loss (gain)	—			54			—			108
Net periodic benefit cost	$	859		$	992		$	1,717		$	1,984

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,
	2019		2018		2019		2018
Service cost	$	692	$	435	$	1,977	$	715
Interest cost	324		292		648		585
Prior service cost	1		1		1		1
Net loss (gain)	134		250		268		500
Net periodic benefit cost	$	1,151	$	978	$	2,894	$	1,801

Contributions

Contributions to the Defined Benefit Pension Plan are cash contributions made directly to the Pension Plan Trust account. Contributions to the Postretirement Healthcare and Supplemental Plans are made in the form of benefit payments. Contributions made in 2019 and anticipated contributions for 2019 and 2020 are as follows (in thousands):



	Contributions Made		Contributions Made		Additional Contributions		Contributions
	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019		Anticipated for 2019		Anticipated for 2020
Defined Benefit Pension Plan	$	—	$	—	$	12,700	$	12,700
Non-pension Defined Benefit Postretirement Healthcare Plans	$	1,108	$	2,217	$	2,217	$	4,271
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	366	$	732	$	732	$	1,562

Commitments and Contingencies:

6 Months Ended

Jun. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

COMMITMENTS AND CONTINGENCIES

There have been no significant changes to commitments and contingencies from those previously disclosed in Note 19 of our Notes to the Consolidated Financial Statements in our 2018 Annual Report on Form 10-K except for those described below.

Platte River Power Authority PPAs


•	On June 26, 2019, Colorado Electric entered into a PPA with Platte River Power Authority to purchase up to 60 MW of wind energy upon construction completion of a new wind project, which is expected in mid-2020. This agreement will expire May 31, 2030.


•	On June 26, 2019, Colorado Electric entered into a PPA with Platte River Power Authority to purchase 25 MW of unit contingent energy. This agreement is effective September 1, 2019 and will expire June 30, 2024.

The following is a schedule of unconditional purchase obligations required under the 25 MW Platte River Power Authority PPA (in thousands):



2019	$	1,831
2020	$	5,490
2021	$	5,475
2022	$	5,475
2023	$	5,475
Thereafter	$	2,729

Discontinued Operations:	6 Months Ended
Discontinued Operations:	Jun. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	DISCONTINUED OPERATIONS Results of operations for discontinued operations were classified as Loss from discontinued operations, net of income taxes in the accompanying Condensed Consolidated Statements of Income. Prior periods relating to our discontinued operations were also reclassified to reflect consistency within our condensed consolidated financial statements. Oil and Gas Segment On November 1, 2017, the BHC Board of Directors approved a complete divestiture of our Oil and Gas segment. We completed the divestiture in 2018.

Income Taxes:	6 Months Ended
Income Taxes:	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income tax benefit (expense) for the Three Months Ended June 30, 2019 Compared to the Three Months Ended June 30, 2018 Income tax benefit (expense) for the three months ended June 30, 2019 was $(2.3) million compared to $(6.5) million reported for the same period in 2018. The decrease is driven by a lower 2019 forecasted annual effective tax rate primarily due to an increase of federal production tax credits and related state investment credits associated with new wind assets; and a current year $1.6 million flow-through discrete tax benefit related to repair costs and certain indirect costs. Income tax benefit (expense) for the Six Months Ended June 30, 2019 Compared to the Six Months Ended June 30, 2018. Income tax benefit (expense) for the six months ended June 30, 2019 was $(20) million compared to $19 million reported for the same period in 2018. The increase in tax expense was primarily due to a prior year $49 million tax benefit resulting from legal entity restructuring partially offset by a prior year $(2.3) million income tax expense associated with changes in the prior estimated impact of tax reform on deferred income taxes. For the six months ended June 30, 2019 the effective tax rate was 13.5% compared to 19.0% excluding the legal entity restructuring and tax reform adjustments, for the same period in 2018. The lower effective tax rate is primarily due to $3.5 million of federal production tax credits and related state investment credits associated with new wind assets, a $1.7 million tax benefit for deferred tax amortization related to tax reform and a $1.6 million flow-through discrete tax benefit related to repair costs and certain indirect costs.

Accrued Liabilities:

6 Months Ended

Jun. 30, 2019

Payables and Accruals [Abstract]

Accrued Liabilities

ACCRUED LIABILITIES

The following amounts by major classification are included in Accrued liabilities in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	June 30, 2019		December 31, 2018
Accrued employee compensation, benefits and withholdings	$	50,996	$	63,742
Accrued property taxes	34,966		42,510
Customer deposits and prepayments	40,716		43,574
Accrued interest and contract adjustment payments	32,213		31,759
CIAC current portion	1,485		1,485
Other (none of which is individually significant)	28,141		32,431
Total accrued liabilities	$	188,517	$	215,501

Leases:

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Leases

LEASES

Lessee

We lease from third parties certain office and operation center facilities, communication tower sites, equipment, and materials storage. Our leases have remaining terms ranging from less than one year to 37 years, including options to extend that are reasonably certain to be exercised.

The components of lease expense were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease cost	Operations and maintenance	$	385	$	696
Finance lease cost:
Amortization of right-of-use asset	Depreciation, depletion and amortization	27		44
Interest on lease liabilities	Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts)	6		9
Total lease cost		$	418	$	749

Supplemental balance sheet information related to leases was as follows (in thousands):



	Balance Sheet Location	As of June 30, 2019
Assets:
Operating lease assets	Other assets, non-current	$	5,161
Finance lease assets	Other assets, non-current	521
Total lease assets		$	5,682

Liabilities:
Current:
Operating leases	Accrued liabilities	$	1,003
Finance lease	Accrued liabilities	106

Noncurrent:
Operating leases	Other deferred credits and other liabilities	4,470
Finance lease	Other deferred credits and other liabilities	419
Total lease liabilities		$	5,998

Supplemental cash flow information related to leases was as follows (in thousands):



	Six Months Ended June 30, 2019
Cash paid included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	528
Operating cash flows from finance lease	$	9
Financing cash flows from finance lease	$	40
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	2,738
Finance lease	$	67



	As of June 30, 2019
Weighted average remaining lease term (years):
Operating leases	8 years
Finance lease	5 years

Weighted average discount rate:
Operating leases	4.25	%
Finance lease	4.20	%

As of June 30, 2019, scheduled maturities of lease liabilities for future years were as follows (in thousands):



	Operating Leases		Finance Lease		Total
2019 ^(a)	$	705	$	63	$	768
2020	976		126		1,102
2021	858		126		984
2022	736		126		862
2023	708		126		834
Thereafter	2,654		10		2,664
Total lease payments^(b)	$	6,637	$	577	$	7,214
Less imputed interest	1,164		52		1,216
Present value of lease liabilities	$	5,473	$	525	$	5,998


(a)	Includes lease liabilities for the remaining six months of 2019.


(b)	Lease payments exclude payments to landlords for common area maintenance, real estate taxes, and insurance.

As previously disclosed in Note 14 of the Notes to the Consolidated Financial Statements in our 2018 Annual Report on Form 10-K, prior to the adoption of ASU 2016-02, Leases (Topic 842), the future minimum payments required under operating lease agreements as of December 31, 2018 were as follows (in thousands):



	Operating Leases
2019	$	1,052
2020	464
2021	344
2022	224
2023	216
Thereafter	1,776
Total lease payments	$	4,076

Leases

LEASES

Lessee

The components of lease expense were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease cost	Operations and maintenance	$	385	$	696
Finance lease cost:
Amortization of right-of-use asset	Depreciation, depletion and amortization	27		44
Interest on lease liabilities	Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts)	6		9
Total lease cost		$	418	$	749

Supplemental balance sheet information related to leases was as follows (in thousands):



	Balance Sheet Location	As of June 30, 2019
Assets:
Operating lease assets	Other assets, non-current	$	5,161
Finance lease assets	Other assets, non-current	521
Total lease assets		$	5,682

Liabilities:
Current:
Operating leases	Accrued liabilities	$	1,003
Finance lease	Accrued liabilities	106

Noncurrent:
Operating leases	Other deferred credits and other liabilities	4,470
Finance lease	Other deferred credits and other liabilities	419
Total lease liabilities		$	5,998

Supplemental cash flow information related to leases was as follows (in thousands):



	Six Months Ended June 30, 2019
Cash paid included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	528
Operating cash flows from finance lease	$	9
Financing cash flows from finance lease	$	40
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	2,738
Finance lease	$	67



	As of June 30, 2019
Weighted average remaining lease term (years):
Operating leases	8 years
Finance lease	5 years

Weighted average discount rate:
Operating leases	4.25	%
Finance lease	4.20	%

As of June 30, 2019, scheduled maturities of lease liabilities for future years were as follows (in thousands):



	Operating Leases		Finance Lease		Total
2019 ^(a)	$	705	$	63	$	768
2020	976		126		1,102
2021	858		126		984
2022	736		126		862
2023	708		126		834
Thereafter	2,654		10		2,664
Total lease payments^(b)	$	6,637	$	577	$	7,214
Less imputed interest	1,164		52		1,216
Present value of lease liabilities	$	5,473	$	525	$	5,998


(a)	Includes lease liabilities for the remaining six months of 2019.


(b)	Lease payments exclude payments to landlords for common area maintenance, real estate taxes, and insurance.



	Operating Leases
2019	$	1,052
2020	464
2021	344
2022	224
2023	216
Thereafter	1,776
Total lease payments	$	4,076

Leases

LEASES

Lessee

The components of lease expense were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease cost	Operations and maintenance	$	385	$	696
Finance lease cost:
Amortization of right-of-use asset	Depreciation, depletion and amortization	27		44
Interest on lease liabilities	Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts)	6		9
Total lease cost		$	418	$	749

Supplemental balance sheet information related to leases was as follows (in thousands):



	Balance Sheet Location	As of June 30, 2019
Assets:
Operating lease assets	Other assets, non-current	$	5,161
Finance lease assets	Other assets, non-current	521
Total lease assets		$	5,682

Liabilities:
Current:
Operating leases	Accrued liabilities	$	1,003
Finance lease	Accrued liabilities	106

Noncurrent:
Operating leases	Other deferred credits and other liabilities	4,470
Finance lease	Other deferred credits and other liabilities	419
Total lease liabilities		$	5,998

Supplemental cash flow information related to leases was as follows (in thousands):



	Six Months Ended June 30, 2019
Cash paid included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	528
Operating cash flows from finance lease	$	9
Financing cash flows from finance lease	$	40
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	2,738
Finance lease	$	67



	As of June 30, 2019
Weighted average remaining lease term (years):
Operating leases	8 years
Finance lease	5 years

Weighted average discount rate:
Operating leases	4.25	%
Finance lease	4.20	%

As of June 30, 2019, scheduled maturities of lease liabilities for future years were as follows (in thousands):



	Operating Leases		Finance Lease		Total
2019 ^(a)	$	705	$	63	$	768
2020	976		126		1,102
2021	858		126		984
2022	736		126		862
2023	708		126		834
Thereafter	2,654		10		2,664
Total lease payments^(b)	$	6,637	$	577	$	7,214
Less imputed interest	1,164		52		1,216
Present value of lease liabilities	$	5,473	$	525	$	5,998


(a)	Includes lease liabilities for the remaining six months of 2019.


(b)	Lease payments exclude payments to landlords for common area maintenance, real estate taxes, and insurance.



	Operating Leases
2019	$	1,052
2020	464
2021	344
2022	224
2023	216
Thereafter	1,776
Total lease payments	$	4,076

Lessor

We lease to third parties certain generating station ground leases, communication tower sites, and a natural gas pipeline. These leases have remaining terms ranging from less than one year to 35 years.

The components of lease revenue were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease income	Revenue	$	567	$	1,205

As of June 30, 2019, scheduled maturities of lease receivables for future years were as follows (in thousands):



	Operating Leases
2019 ^(a)	$	1,085
2020	2,010
2021	1,843
2022	1,793
2023	1,799
Thereafter	55,481
Total lease receivables	$	64,011

(a)

Includes lease receivables for the remaining six months of 2019.

Subsequent Event (Notes)	6 Months Ended
Subsequent Event (Notes)	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENTS On August 2, 2019, Black Hills Wyoming and Wyoming Electric filed a request with FERC for approval of a new 60 MW PPA. If approved, Black Hills Wyoming will deliver 60 MW of energy to Wyoming Electric from its Wygen I power plant starting January 1, 2023, and continuing for 20 years. A decision from FERC is expected by the end of 2019.

Management's Statement (Policies)

6 Months Ended

Jun. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Segment Reporting

We conduct our operations through the following reportable segments: Electric Utilities, Gas Utilities, Power Generation and Mining. Our reportable segments are based on our method of internal reporting, which is generally segregated by differences in products, services and regulation. All of our operations and assets are located within the United States.

Effective January 1, 2019, we changed our measure of segment performance to adjusted operating income, which impacted our segment disclosures for all periods presented. See Note 3 for more information.

On November 1, 2017, the BHC board of directors approved a complete divestiture of our Oil and Gas segment. We completed the divestiture in 2018. The Oil and Gas segment assets and liabilities were classified as held for sale and the results of operations were shown in income (loss) from discontinued operations, except for certain general and administrative costs and interest expense which do not meet the criteria for income (loss) from discontinued operations. At the time the assets were classified as held for sale, depreciation, depletion and amortization expenses were no longer recorded. Unless otherwise noted, the amounts presented in the accompanying notes to the Condensed Consolidated Financial Statements relate to the Company’s continuing operations. See Note 17 for more information on discontinued operations.

Use of Estimates and Basis of Presentation

The information furnished in the accompanying Condensed Consolidated Financial Statements reflects certain estimates required and all adjustments, including accruals, which are, in the opinion of management, necessary for a fair presentation of the June 30, 2019 and December 31, 2018 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. 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, 2019 and June 30, 2018, and our financial condition as of June 30, 2019 and December 31, 2018 are not necessarily indicative of the results of operations and financial condition to be expected 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

Recently Issued Accounting Standards

Simplifying the Test for Goodwill Impairment, 2017-04

In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment by eliminating step 2 from the goodwill impairment test. Under the new guidance, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss will be recognized in an amount equal to that excess, limited to the amount of goodwill allocated to that reporting unit. The new standard is effective for interim and annual reporting periods beginning after December 1, 2019, applied on a prospective basis with early adoption permitted. We do not anticipate the adoption of this guidance to have any impact on our financial position, results of operations or cash flows.

Financial Instruments -- Credit Losses: Measurement of Credit Losses on Financial Instruments, ASU 2018-19

In June 2016, the FASB issued ASU 2016-13, Financial Instruments -- Credit Losses: Measurement of Credit Losses on Financial Instruments, which was subsequently amended by ASU 2018-19 in November 2018. The standard introduces new accounting guidance for credit losses on financial instruments within its scope, including trade receivables. This new guidance adds an impairment model that is based on expected losses rather than incurred losses. It is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We are currently assessing the impacts of adopting this standard.

Recently Adopted Accounting Standards

Leases, ASU 2016-02

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) to increase transparency and comparability among organizations by requiring the recognition of right-of-use assets and lease liabilities on the balance sheet for most leases, whereas previously only financing-type lease liabilities (capital leases) were recognized on the balance sheet. Under the new standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases.

We adopted the standard effective January 1, 2019. We elected not to recast comparative periods coinciding with the new lease standard transition and will report these comparative periods as presented under previous lease guidance. In addition, we elected the package of practical expedients permitted under the transition guidance with the new standard, which among other things, allowed us to carry forward the historical lease classification. We also elected the practical expedient related to land easements, allowing us to carry forward our accounting treatment for existing land easement agreements.

Adoption of the new standard resulted in the recording of an operating lease right-of-use asset of $3.1 million, an operating lease obligation liability of $3.2 million, and an accrued rent receivable of $4.5 million, as of January 1, 2019. The cumulative effect of the adoption, net of tax impact, was $3.4 million, which was recorded as an adjustment to retained earnings.

Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities, ASU 2017-12

Effective January 1, 2019, we adopted ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. This standard better aligns risk management activities and financial reporting for hedging relationships, simplifies hedge accounting requirements and improves disclosures of hedging arrangements. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows.

Revenue Recognition



Three Months Ended June 30, 2019	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues			Total
Customer types:	(in thousands)
Retail	$	139,732	$	123,630	$	—	$	12,428	$	(7,041	)	$	268,749
Transportation	—		28,623		—		—		(276		)	28,347
Wholesale	6,781		—		15,062		—		(13,296		)	8,547
Market - off-system sales	3,448		161		—		—		(1,335		)	2,274
Transmission/Other	14,416		11,612		—		—		(4,199		)	21,829
Revenue from contracts with customers	$	164,377	$	164,026	$	15,062	$	12,428	$	(26,147	)	$	329,746
Other revenues	1,977		1,443		9,646		617		(9,541		)	4,142
Total revenues	$	166,354	$	165,469	$	24,708	$	13,045	$	(35,688	)	$	333,888

Timing of revenue recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	12,428	$	(7,041	)	$	5,387
Services transferred over time	164,377		164,026		15,062		—		(19,106		)	324,359
Revenue from contracts with customers	$	164,377	$	164,026	$	15,062	$	12,428	$	(26,147	)	$	329,746



Three Months Ended June 30, 2018	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues			Total
Customer Types:
Retail	$	145,377	$	135,863	$	—	$	16,345	$	(7,979	)	$	289,606
Transportation	—		29,011		—		—		(301		)	28,710
Wholesale	8,191		—		13,603		—		(12,473		)	9,321
Market - Off-System Sales	4,938		162		—		—		(1,660		)	3,440
Transmission/Other	13,356		11,672		—		—		(3,644		)	21,384
Revenue from contracts with customers	$	171,862	$	176,708	$	13,603	$	16,345	$	(26,057	)	$	352,461
Other Revenues	1,754		912		9,141		554		(9,118		)	3,243
Total Revenues	$	173,616	$	177,620	$	22,744	$	16,899	$	(35,175	)	$	355,704

Timing of Revenue Recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	16,345	$	(7,978	)	$	8,367
Services transferred over time	171,862		176,708		13,603		—		(18,079		)	344,094
Revenue from Contracts with Customers	$	171,862	$	176,708	$	13,603	$	16,345	$	(26,057	)	$	352,461



Six Months Ended June 30, 2019	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer types:	(in thousands)
Retail	$	293,195	$	477,905	$	—	$	28,257	$	(15,169	)	$	784,188
Transportation	—		73,140		—		—		(708		)	72,432
Wholesale	15,124		—		30,531		—		(26,509		)	19,146
Market - off-system sales	10,140		378		—		—		(3,559		)	6,959
Transmission/Other	28,591		24,802		—		—		(8,402		)	44,991
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716
Other revenues	2,231		324		19,422		1,217		(19,212		)	3,982
Total revenues	$	349,281	$	576,549	$	49,953	$	29,474	$	(73,559	)	$	931,698

Timing of revenue recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	28,257	$	(15,169	)	$	13,088
Services transferred over time	347,050		576,225		30,531		—		(39,178		)	914,628
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716



Six Months Ended June 30, 2018	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer Types:
Retail	$	292,434	$	477,257	$	—	$	32,902	$	(15,821	)	$	786,772
Transportation	—		70,681		—		—		(710		)	69,971
Wholesale	17,241		—		28,371		—		(25,521		)	20,091
Market - Off-System Sales	9,082		589		—		—		(4,182		)	5,489
Transmission/Other	26,427		24,341		—		—		(7,275		)	43,493
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816
Other Revenues	1,987		2,096		18,311		1,125		(18,242		)	5,277
Total Revenues	$	347,171	$	574,964	$	46,682	$	34,027	$	(71,751	)	$	931,093

Timing of Revenue Recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	32,902	$	(15,820	)	$	17,082
Services transferred over time	345,184		572,868		28,371		—		(37,689		)	908,734
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816

(a)

Contract Balances

Revenue (Tables)

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue



Six Months Ended June 30, 2019	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer types:	(in thousands)
Retail	$	293,195	$	477,905	$	—	$	28,257	$	(15,169	)	$	784,188
Transportation	—		73,140		—		—		(708		)	72,432
Wholesale	15,124		—		30,531		—		(26,509		)	19,146
Market - off-system sales	10,140		378		—		—		(3,559		)	6,959
Transmission/Other	28,591		24,802		—		—		(8,402		)	44,991
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716
Other revenues	2,231		324		19,422		1,217		(19,212		)	3,982
Total revenues	$	349,281	$	576,549	$	49,953	$	29,474	$	(73,559	)	$	931,698

Timing of revenue recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	28,257	$	(15,169	)	$	13,088
Services transferred over time	347,050		576,225		30,531		—		(39,178		)	914,628
Revenue from contracts with customers	$	347,050	$	576,225	$	30,531	$	28,257	$	(54,347	)	$	927,716



Six Months Ended June 30, 2018	Electric Utilities		Gas Utilities		Power Generation ^(a)		Mining		Inter-company Revenues ^(a)			Total
Customer Types:
Retail	$	292,434	$	477,257	$	—	$	32,902	$	(15,821	)	$	786,772
Transportation	—		70,681		—		—		(710		)	69,971
Wholesale	17,241		—		28,371		—		(25,521		)	20,091
Market - Off-System Sales	9,082		589		—		—		(4,182		)	5,489
Transmission/Other	26,427		24,341		—		—		(7,275		)	43,493
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816
Other Revenues	1,987		2,096		18,311		1,125		(18,242		)	5,277
Total Revenues	$	347,171	$	574,964	$	46,682	$	34,027	$	(71,751	)	$	931,093

Timing of Revenue Recognition:
Services transferred at a point in time	$	—	$	—	$	—	$	32,902	$	(15,820	)	$	17,082
Services transferred over time	345,184		572,868		28,371		—		(37,689		)	908,734
Revenue from contracts with customers	$	345,184	$	572,868	$	28,371	$	32,902	$	(53,509	)	$	925,816

(a)

Business Segment Information (Tables)

6 Months Ended

Jun. 30, 2019

Segment Reporting Information, Additional Information [Abstract]

Segment Reporting

Segment information and Corporate and Other is as follows (in thousands):




Three Months Ended June 30, 2019	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	159,140	$	1,977	$	5,237		$	—		$	166,354
Gas Utilities	163,303		1,443		723			—			165,469
Power Generation ^(a)	1,765		434		13,297			9,212			24,708
Mining	5,538		288		6,890			329			13,045
Inter-company eliminations ^(a)	—		—		(26,147		)	(9,541		)	(35,688		)
Total	$	329,746	$	4,142	$	—		$	—		$	333,888




Three Months Ended June 30, 2018	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	166,565	$	1,754	$	5,297		$	—		$	173,616
Gas Utilities	176,399		912		309			—			177,620
Power Generation ^(a)	1,130		348		12,473			8,793			22,744
Mining	8,367		229		7,978			325			16,899
Inter-company eliminations ^(a)	—		—		(26,057		)	(9,118		)	(35,175		)
Total	$	352,461	$	3,243	$	—		$	—		$	355,704



Six Months Ended June 30, 2019	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
Six Months Ended June 30, 2019	Contract Customers		Other Revenues		Contract Customers			Other Revenues			Total Revenues
Segment:
Electric Utilities	$	335,803	$	2,231	$	11,247		$	—		$	349,281
Gas Utilities	574,803		324		1,422			—			576,549
Power Generation ^(a)	4,022		870		26,509			18,552			49,953
Mining	13,088		557		15,169			660			29,474
Inter-company eliminations ^(a)	—		—		(54,347		)	(19,212		)	(73,559		)
Total	$	927,716	$	3,982	$	—		$	—		$	931,698




Six Months Ended June 30, 2018	External Operating Revenue				Inter-company Operating Revenue						Total Revenues
	Contract Customers		Other Revenues		Contract Customers			Other Revenues
Segment:
Electric Utilities	$	333,743	$	1,987	$	11,441		$	—		$	347,171
Gas Utilities	572,141		2,096		727			—			574,964
Power Generation ^(a)	2,850		718		25,521			17,593			46,682
Mining	17,082		476		15,820			649			34,027
Inter-company eliminations ^(a)	—		—		(53,509		)	(18,242		)	(71,751		)
Total	$	925,816	$	5,277	$	—		$	—		$	931,093

(a)




	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Adjusted operating income:
Electric Utilities ^(a)	$	33,546		$	41,200		$	74,566		$	79,680
Gas Utilities	8,557			16,485			111,871			111,928
Power Generation ^(a)	10,156			8,877			22,123			20,652
Mining	1,640			3,825			5,977			8,096
Corporate and Other ^(a)	102			(836		)	(405		)	(2,531		)
Operating income	54,001			69,551			214,132			217,825

Interest expense, net	(34,265		)	(34,534		)	(68,982		)	(69,529		)
Other income (expense), net	264			(1,309		)	(525		)	(1,413		)
Income tax benefit (expense) ^(b)	(2,307		)	(6,541		)	(19,570		)	19,261
Income from continuing operations	17,693			27,167			125,055			166,144
Net (loss) from discontinued operations	—			(2,427		)	—			(4,770		)
Net income	17,693			24,740			125,055			161,374
Net income attributable to noncontrolling interest	(3,110		)	(2,823		)	(6,664		)	(6,453		)
Net income available for common stock	$	14,583		$	21,917		$	118,391		$	154,921

___________


(a)	Due to the changes in our segment disclosures, Adjusted operating income was revised for the three and six months ended June 30, 2018, which resulted in an increase (decrease) as follows (in millions):



Segment	Three Months Ended June 30, 2018			Six Months Ended June 30, 2018
Electric Utilities	$	1.6		$	3.3
Power Generation	(1.4		)	(3.0		)
Corporate and Other	(0.2		)	(0.3		)
	$	—		$	—

(b)

Income tax benefit (expense) for the six months ended June 30, 2018 included a $49 million tax benefit resulting from legal entity restructuring. See Note 18 for more information.

Reconciliation of Assets from Segment to Consolidated

Segment information and Corporate and Other 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, 2019		December 31, 2018
Segment:
Electric Utilities ^(a)	$	2,777,803	$	2,707,695
Gas Utilities	3,645,840		3,623,475
Power Generation ^(a)	379,140		342,085
Mining	62,491		80,594
Corporate and Other	216,179		209,478
Total assets	$	7,081,453	$	6,963,327

___________

(a)

Accounts Receivable (Tables)

6 Months Ended

Jun. 30, 2019

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, 2019	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	39,982	$	31,573	$	(526	)	$	71,029
Gas Utilities	67,686		23,753		(4,391		)	87,048
Power Generation	2,867		—		—			2,867
Mining	2,505		—		—			2,505
Corporate	3,233		—		(169		)	3,064
Total	$	116,273	$	55,326	$	(5,086	)	$	166,513



	Accounts		Unbilled		Less Allowance for			Accounts
December 31, 2018	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
Electric Utilities	$	39,721	$	35,125	$	(448	)	$	74,398
Gas Utilities	96,123		90,521		(2,592		)	184,052
Power Generation	1,876		—		—			1,876
Mining	3,988		—		—			3,988
Corporate	5,008		—		(169		)	4,839
Total	$	146,716	$	125,646	$	(3,209	)	$	269,153

Regulatory Accounting (Tables)

6 Months Ended

Jun. 30, 2019

Regulatory Assets and Liabilities Disclosure [Abstract]

Schedule of Regulatory Assets and Liabilities

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



	June 30, 2019			December 31, 2018
Regulatory assets
Deferred energy and fuel cost adjustments ^(a)	$	34,257		$	29,661
Deferred gas cost adjustments ^(a)	2,342			3,362
Gas price derivatives ^(a)	3,945			6,201
Deferred taxes on AFUDC^(b)	7,716			7,841
Employee benefit plans ^(c)	109,899			110,524
Environmental^(a)	931			959
Loss on reacquired debt^(a)	20,140			21,001
Renewable energy standard adjustment ^(a)	1,994			1,722
Deferred taxes on flow through accounting^(c)	36,552			31,044
Decommissioning costs ^(b)	11,518			11,700
Gas supply contract termination ^(a)	11,413			14,310
Other regulatory assets^(a)	42,342			45,910
Total regulatory assets	283,049			284,235
Less current regulatory assets	(48,925		)	(48,776		)
Regulatory assets, non-current	$	234,124		$	235,459

Regulatory liabilities
Deferred energy and gas costs^(a)	$	16,808		$	6,991
Employee benefit plan costs and related deferred taxes^(c)	41,814			42,533
Cost of removal^(a)	158,477			150,123
Excess deferred income taxes ^(c)	307,871			310,562
TCJA revenue reserve	11,436			18,032
Other regulatory liabilities^(c)	18,150			12,553
Total regulatory liabilities	554,556			540,794
Less current regulatory liabilities	(39,642		)	(29,810		)
Regulatory liabilities, non-current	$	514,914		$	510,984

__________


(a)	We are allowed 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.

Materials, Supplies and Fuel (Tables)

6 Months Ended

Jun. 30, 2019

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, 2019		December 31, 2018
Materials and supplies	$	80,639	$	75,081
Fuel - Electric Utilities	2,350		2,850
Natural gas in storage held for distribution	19,841		39,368
Total materials, supplies and fuel	$	102,830	$	117,299

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2019

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 was as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018

Net income available for common stock	$	14,583	$	21,917	$	118,391	$	154,921

Weighted average shares - basic	60,467		53,355		60,195		53,337
Dilutive effect of:
Equity Units ^(a)	—		1,057		—		904
Equity compensation	139		108		138		120
Weighted average shares - diluted	60,606		54,520		60,333		54,361

__________


(a)	Calculated using the treasury stock method. On November 1, 2018, we completed settlement of the stock purchase contracts that were components of the Equity Units issued in November 2015.

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following outstanding securities were 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,
	2019	2018	2019	2018

Equity compensation	—	15	—	17
Anti-dilutive shares	—	15	—	17

Notes Payable, Current Maturities and Debt (Tables)

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

Schedule of Short-term Debt

We had the following notes payable outstanding in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	June 30, 2019				December 31, 2018
	Balance Outstanding		Letters of Credit		Balance Outstanding		Letters of Credit
Revolving Credit Facility	$	—	$	10,429	$	—	$	22,311
CP Program	102,500		—		185,620		—
Total	$	102,500	$	10,429	$	185,620	$	22,311

Risk Management Activities (Tables)

6 Months Ended

Jun. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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



	June 30, 2019		December 31, 2018
	Notional (MMBtus)	Maximum Term (months)^(a)	Notional (MMBtus)	Maximum Term (months)^(a)
Natural gas futures purchased	2,480,000	18	4,000,000	24
Natural gas options purchased, net	2,160,000	9	4,320,000	13
Natural gas basis swaps purchased	2,360,000	18	3,960,000	24
Natural gas over-the-counter swaps, net ^(b)	6,020,000	23	3,660,000	24
Natural gas physical contracts, net ^(c)	1,717,075	9	18,325,852	30

__________


(a)	Term reflects the maximum forward period hedged.


(b)	As of June 30, 2019, 2,130,000 MMBtus were designated as cash flow hedges.

(c)

Volumes exclude contracts that qualify for the normal purchase, normal sales exception.

Derivative Instruments, Gain (Loss)



Three Months Ended June 30, 2019
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(713	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	83
Total		$	(630	)



Three Months Ended June 30, 2018
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(713	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	(163		)
Total		$	(876	)



Six Months Ended June 30, 2019
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(1,426	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	637
Total		$	(789	)



Six Months Ended June 30, 2018
(in thousands)
Derivatives in Cash Flow Hedging Relationships	Location of Reclassifications from AOCI into Income	Amount of Gain/(Loss) Reclassified from AOCI into Income
Interest rate swaps	Interest expense	$	(1,426	)
Commodity derivatives	Fuel, purchased power and cost of natural gas sold	(784		)
Total		$	(2,210	)




	Three Months Ended June 30,
	2019			2018
	(in thousands)
Increase (decrease) in fair value:
Forward commodity contracts	$	(518	)	$	48
Recognition of (gains) losses in earnings due to settlements:
Interest rate swaps	713			713
Forward commodity contracts	(83		)	163
Total other comprehensive income (loss) from hedging	$	112		$	924



	Six Months Ended June 30,
	2019			2018
	(in thousands)
Increase (decrease) in fair value:
Forward commodity contracts	$	(284	)	$	(249	)
Recognition of (gains) losses in earnings due to settlements:
Interest rate swaps	1,426			1,426
Forward commodity contracts	(637		)	784
Total other comprehensive income (loss) from hedging	$	505		$	1,961

Derivatives Not Designated as Hedge Instruments




		Three Months Ended June 30,
		2019			2018
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income			Amount of Gain/(Loss) on Derivatives Recognized in Income

Commodity derivatives	Fuel, purchased power and cost of natural gas sold	$	(1,185	)	$	771
		$	(1,185	)	$	771



		Six Months Ended June 30,
		2019			2018
Derivatives Not Designated as Hedging Instruments	Location of Gain/(Loss) on Derivatives Recognized in Income	Amount of Gain/(Loss) on Derivatives Recognized in Income			Amount of Gain/(Loss) on Derivatives Recognized in Income

Commodity derivatives	Fuel, purchased power and cost of natural gas sold	$	(1,160	)	$	1,025
		$	(1,160	)	$	1,025

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value Hierarchy, Measured on Recurring Basis

Recurring Fair Value Measurements



	As of June 30, 2019
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Utilities	$	—	$	986	$	—	$	(575	)	$	411
Total	$	—	$	986	$	—	$	(575	)	$	411

Liabilities:
Commodity derivatives — Utilities	$	—	$	5,567	$	—	$	(3,945	)	$	1,622
Total	$	—	$	5,567	$	—	$	(3,945	)	$	1,622



	As of December 31, 2018
	Level 1		Level 2		Level 3		Cash Collateral and Counterparty Netting			Total
	(in thousands)
Assets:
Commodity derivatives — Utilities	$	—	$	2,927	$	—	$	(1,408	)	$	1,519
Total	$	—	$	2,927	$	—	$	(1,408	)	$	1,519

Liabilities:
Commodity derivatives — Utilities	$	—	$	6,801	$	—	$	(5,794	)	$	1,007
Total	$	—	$	6,801	$	—	$	(5,794	)	$	1,007

Schedule of Derivative Instruments Balance Sheet Location

The following table presents the fair value and balance sheet classification of our derivative instruments (in thousands) as of:



	Balance Sheet Location	June 30, 2019			December 31, 2018
Derivatives designated as hedges:
Asset derivative instruments:
Current commodity derivatives	Derivative assets — current	$	—		$	415
Noncurrent commodity derivatives	Other assets, non-current	4			18
Liability derivative instruments:
Current commodity derivatives	Derivative liabilities — current	(449		)	(114		)
Noncurrent commodity derivatives	Other deferred credits and other liabilities	(58		)	(4		)
Total derivatives designated as hedges		$	(503	)	$	315

Derivatives not designated as hedges:
Asset derivative instruments:
Current commodity derivatives	Derivative assets — current	$	405		$	1,085
Noncurrent commodity derivatives	Other assets, non-current	2			1
Liability derivative instruments:
Current commodity derivatives	Derivative liabilities — current	(1,042		)	(833		)
Noncurrent commodity derivatives	Other deferred credits and other liabilities	(73		)	(56		)
Total derivatives not designated as hedges		$	(708	)	$	197

Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

were as follows (in thousands) as of:



	June 30, 2019				December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current maturities ^{(a) (b)}	$	3,055,415	$	3,337,314	$	2,956,578	$	3,039,108

__________


(a)	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.

(b)

Carrying amount of long-term debt is net of deferred financing costs.

Other Comprehensive Income (Loss) (Tables)

6 Months Ended

Jun. 30, 2019

Statement of Comprehensive Income [Abstract]

Reclassification Out of Accumulated Other Comprehensive Income (Loss)



	Location on the Condensed Consolidated Statements of Income	Amount Reclassified from AOCI
		Three Months Ended						Six Months Ended
		June 30, 2019			June 30, 2018			June 30, 2019			June 30, 2018
Gains and (losses) on cash flow hedges:
Interest rate swaps	Interest expense	$	(713	)	$	(713	)	$	(1,426	)	$	(1,426	)
Commodity contracts	Fuel, purchased power and cost of natural gas sold	83			(163		)	637			(784		)
		(630		)	(876		)	(789		)	(2,210		)
Income tax	Income tax benefit (expense)	153			197			188			494
Total reclassification adjustments related to cash flow hedges, net of tax		$	(477	)	$	(679	)	$	(601	)	$	(1,716	)

Amortization of components of defined benefit plans:
Prior service cost	Operations and maintenance	$	20		$	44		$	39		$	89

Actuarial gain (loss)	Operations and maintenance	(221		)	(622		)	(441		)	(1,244		)
		(201		)	(578		)	(402		)	(1,155		)
Income tax	Income tax benefit (expense)	47			126			95			252
Total reclassification adjustments related to defined benefit plans, net of tax		$	(154	)	$	(452	)	$	(307	)	$	(903	)
Total reclassifications		$	(631	)	$	(1,131	)	$	(908	)	$	(2,619	)

Schedule of Accumulated Other Comprehensive Income (Loss)

Balances by classification included within AOCI, net of tax on the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands):



	Interest Rate Swaps			Commodity Derivatives			Employee Benefit Plans			Total
As of December 31, 2018	$	(17,307	)	$	328		$	(9,937	)	$	(26,916	)
Other comprehensive income (loss)
before reclassifications	—			(219		)	—			(219		)
Amounts reclassified from AOCI	1,091			(490		)	307			908
As of June 30, 2019	$	(16,216	)	$	(381	)	$	(9,630	)	$	(26,227	)


	Interest Rate Swaps			Commodity Derivatives			Employee Benefit Plans			Total
Balance as of December 31, 2017	$	(19,581	)	$	(518	)	$	(21,103	)	$	(41,202	)
Other comprehensive income (loss)
before reclassifications	—			(198		)	—			(198		)
Amounts reclassified from AOCI	1,122			594			903			2,619
Reclassifications of certain tax effects from AOCI	15			—			3			18
As of June 30, 2018	$	(18,444	)	$	(122	)	$	(20,197	)	$	(38,763	)

Supplemental Disclosure of Cash Flow Information (Tables)

6 Months Ended

Jun. 30, 2019

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information



Six Months Ended	June 30, 2019			June 30, 2018
	(in thousands)
Non-cash investing and financing activities —
Property, plant and equipment acquired with accrued liabilities	$	83,486		$	37,168

Cash (paid) refunded during the period —
Interest (net of amounts capitalized)	$	(67,624	)	$	(67,119	)
Income taxes	$	1,790		$	(14,837	)

Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2019

Defined Benefit Plan [Abstract]

Schedule of Net Benefit Costs

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Service cost	$	1,345		$	1,709		$	2,691		$	3,417
Interest cost	4,344			3,868			8,687			7,735
Expected return on plan assets	(6,100		)	(6,185		)	(12,200		)	(12,370		)
Prior service cost	7			14			13			29
Net loss (gain)	940			2,157			1,881			4,315
Net periodic benefit cost	$	536		$	1,563		$	1,072		$	3,126

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,
	2019			2018			2019			2018
Service cost	$	454		$	572		$	908		$	1,145
Interest cost	563			521			1,123			1,042
Expected return on plan assets	(58		)	(56		)	(115		)	(113		)
Prior service cost (benefit)	(100		)	(99		)	(199		)	(198		)
Net loss (gain)	—			54			—			108
Net periodic benefit cost	$	859		$	992		$	1,717		$	1,984

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,
	2019		2018		2019		2018
Service cost	$	692	$	435	$	1,977	$	715
Interest cost	324		292		648		585
Prior service cost	1		1		1		1
Net loss (gain)	134		250		268		500
Net periodic benefit cost	$	1,151	$	978	$	2,894	$	1,801

Schedule of Defined Benefit Plans Contributions

Contributions made in 2019 and anticipated contributions for 2019 and 2020 are as follows (in thousands):



	Contributions Made		Contributions Made		Additional Contributions		Contributions
	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019		Anticipated for 2019		Anticipated for 2020
Defined Benefit Pension Plan	$	—	$	—	$	12,700	$	12,700
Non-pension Defined Benefit Postretirement Healthcare Plans	$	1,108	$	2,217	$	2,217	$	4,271
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	366	$	732	$	732	$	1,562

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]

The following is a schedule of unconditional purchase obligations required under the 25 MW Platte River Power Authority PPA (in thousands):



2019	$	1,831
2020	$	5,490
2021	$	5,475
2022	$	5,475
2023	$	5,475
Thereafter	$	2,729

Accrued Liabilities (Tables)

6 Months Ended

Jun. 30, 2019

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities

The following amounts by major classification are included in Accrued liabilities in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of:



	June 30, 2019		December 31, 2018
Accrued employee compensation, benefits and withholdings	$	50,996	$	63,742
Accrued property taxes	34,966		42,510
Customer deposits and prepayments	40,716		43,574
Accrued interest and contract adjustment payments	32,213		31,759
CIAC current portion	1,485		1,485
Other (none of which is individually significant)	28,141		32,431
Total accrued liabilities	$	188,517	$	215,501

Leases (Tables)

6 Months Ended

Jun. 30, 2019

Lessee Disclosure [Abstract]

Lease, Cost

The components of lease expense were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease cost	Operations and maintenance	$	385	$	696
Finance lease cost:
Amortization of right-of-use asset	Depreciation, depletion and amortization	27		44
Interest on lease liabilities	Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts)	6		9
Total lease cost		$	418	$	749

Lessee - Supplemental Balance Sheet Information

Supplemental balance sheet information related to leases was as follows (in thousands):



	Balance Sheet Location	As of June 30, 2019
Assets:
Operating lease assets	Other assets, non-current	$	5,161
Finance lease assets	Other assets, non-current	521
Total lease assets		$	5,682

Liabilities:
Current:
Operating leases	Accrued liabilities	$	1,003
Finance lease	Accrued liabilities	106

Noncurrent:
Operating leases	Other deferred credits and other liabilities	4,470
Finance lease	Other deferred credits and other liabilities	419
Total lease liabilities		$	5,998

Lessee - Supplemental Cash Flow Information

Supplemental cash flow information related to leases was as follows (in thousands):



	Six Months Ended June 30, 2019
Cash paid included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	528
Operating cash flows from finance lease	$	9
Financing cash flows from finance lease	$	40
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	2,738
Finance lease	$	67

Lessee - Supplemental Weighted Average Schedule



	As of June 30, 2019
Weighted average remaining lease term (years):
Operating leases	8 years
Finance lease	5 years

Weighted average discount rate:
Operating leases	4.25	%
Finance lease	4.20	%

Lessee - Finance Lease, Liability, Maturity

As of June 30, 2019, scheduled maturities of lease liabilities for future years were as follows (in thousands):



	Operating Leases		Finance Lease		Total
2019 ^(a)	$	705	$	63	$	768
2020	976		126		1,102
2021	858		126		984
2022	736		126		862
2023	708		126		834
Thereafter	2,654		10		2,664
Total lease payments^(b)	$	6,637	$	577	$	7,214
Less imputed interest	1,164		52		1,216
Present value of lease liabilities	$	5,473	$	525	$	5,998


(a)	Includes lease liabilities for the remaining six months of 2019.

(b)

Lease payments exclude payments to landlords for common area maintenance, real estate taxes, and insurance.

Lessee, Operating Lease, Liability, Maturity

As of June 30, 2019, scheduled maturities of lease liabilities for future years were as follows (in thousands):



	Operating Leases		Finance Lease		Total
2019 ^(a)	$	705	$	63	$	768
2020	976		126		1,102
2021	858		126		984
2022	736		126		862
2023	708		126		834
Thereafter	2,654		10		2,664
Total lease payments^(b)	$	6,637	$	577	$	7,214
Less imputed interest	1,164		52		1,216
Present value of lease liabilities	$	5,473	$	525	$	5,998


(a)	Includes lease liabilities for the remaining six months of 2019.


(b)	Lease payments exclude payments to landlords for common area maintenance, real estate taxes, and insurance.



	Operating Leases
2019	$	1,052
2020	464
2021	344
2022	224
2023	216
Thereafter	1,776
Total lease payments	$	4,076

Lessor Disclosure [Abstract]

Operating Lease, Lease Income

The components of lease revenue were as follows (in thousands):



	Income Statement Location	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
Operating lease income	Revenue	$	567	$	1,205

Lessor - Operating and Finance Lease, Liability, Maturity

As of June 30, 2019, scheduled maturities of lease receivables for future years were as follows (in thousands):



	Operating Leases
2019 ^(a)	$	1,085
2020	2,010
2021	1,843
2022	1,793
2023	1,799
Thereafter	55,481
Total lease receivables	$	64,011

(a)

Includes lease receivables for the remaining six months of 2019.

Management's Statement (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease - right of use assets	$ 5,161
Operating lease obligation liability	5,473
Cumulative effect of the adoption, net of tax impact	$ (3)	$ 3,390
Leases, ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease - right of use assets			$ 3,100
Operating lease obligation liability			3,200
Accrued rent receivable			4,500
Cumulative effect of the adoption, net of tax impact			$ 3,400

Revenue: Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 329,746	$ 352,461	$ 927,716	$ 925,816
Total revenues	333,888	355,704	931,698	931,093
Recasting of Intercompany Capital Lease
Disaggregation of Revenue [Line Items]
Changes To Our Segment Performance Measure - Revenues		0		0
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,387	8,367	13,088	17,082
Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	324,359	344,094	914,628	908,734
Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	4,142	3,243	3,982	5,277
Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	268,749	289,606	784,188	786,772
Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	28,347	28,710	72,432	69,971
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8,547	9,321	19,146	20,091
Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,274	3,440	6,959	5,489
Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21,829	21,384	44,991	43,493
Inter-company Revenues
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(26,147)	(26,057)	(54,347)	(53,509)
Total revenues	(35,688)	(35,175)	(73,559)	(71,751)
Inter-company Revenues \| Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(7,041)	(7,978)	(15,169)	(15,820)
Inter-company Revenues \| Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(19,106)	(18,079)	(39,178)	(37,689)
Inter-company Revenues \| Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	(9,541)	(9,118)	(19,212)	(18,242)
Inter-company Revenues \| Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(7,041)	(7,979)	(15,169)	(15,821)
Inter-company Revenues \| Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(276)	(301)	(708)	(710)
Inter-company Revenues \| Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(13,296)	(12,473)	(26,509)	(25,521)
Inter-company Revenues \| Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1,335)	(1,660)	(3,559)	(4,182)
Inter-company Revenues \| Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(4,199)	(3,644)	(8,402)	(7,275)
Electric Utilities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164,377	171,862	347,050	345,184
Total revenues	166,354	173,616	349,281	347,171
Electric Utilities \| Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Electric Utilities \| Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164,377	171,862	347,050	345,184
Electric Utilities \| Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,977	1,754	2,231	1,987
Electric Utilities \| Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	139,732	145,377	293,195	292,434
Electric Utilities \| Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Electric Utilities \| Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,781	8,191	15,124	17,241
Electric Utilities \| Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,448	4,938	10,140	9,082
Electric Utilities \| Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14,416	13,356	28,591	26,427
Gas Utilities
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164,026	176,708	576,225	572,868
Total revenues	165,469	177,620	576,549	574,964
Gas Utilities \| Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Gas Utilities \| Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164,026	176,708	576,225	572,868
Gas Utilities \| Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	1,443	912	324	2,096
Gas Utilities \| Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	123,630	135,863	477,905	477,257
Gas Utilities \| Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	28,623	29,011	73,140	70,681
Gas Utilities \| Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Gas Utilities \| Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	161	162	378	589
Gas Utilities \| Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,612	11,672	24,802	24,341
Power Generation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	15,062	13,603	30,531	28,371
Total revenues	24,708	22,744	49,953	46,682
Power Generation \| Recasting of Intercompany Capital Lease
Disaggregation of Revenue [Line Items]
Changes To Our Segment Performance Measure - Revenues		900		1,700
Power Generation \| Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Power Generation \| Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	15,062	13,603	30,531	28,371
Power Generation \| Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	9,646	9,141	19,422	18,311
Power Generation \| Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Power Generation \| Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Power Generation \| Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	15,062	13,603	30,531	28,371
Power Generation \| Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Power Generation \| Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Mining
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,428	16,345	28,257	32,902
Total revenues	13,045	16,899	29,474	34,027
Mining \| Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,428	16,345	28,257	32,902
Mining \| Services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Mining \| Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	617	554	1,217	1,125
Mining \| Retail - Electric , Natural Gas and Coal
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,428	16,345	28,257	32,902
Mining \| Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Mining \| Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Mining \| Market - off-system sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Mining \| Transmission/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0

Business Segment Information: Information Relating to Segment Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information
Revenue from contracts with customers	$ 329,746	$ 352,461	$ 927,716	$ 925,816
Revenues	333,888	355,704	931,698	931,093
Operating income	54,001	69,551	214,132	217,825
Interest expense, net	(34,265)	(34,534)	(68,982)	(69,529)
Other Nonoperating Income (Expense) Including Allowance For Funds Used During Construction, Equity	264	(1,309)	(525)	(1,413)
Income tax benefit (expense)	(2,307)	(6,541)	(19,570)	19,261
Income from continuing operations	17,693	27,167	125,055	166,144
Net (loss) from discontinued operations	0	(2,427)	0	(4,770)
Net income	17,693	24,740	125,055	161,374
Net income attributable to noncontrolling interest	(3,110)	(2,823)	(6,664)	(6,453)
Net income available for common stock	14,583	21,917	118,391	154,921
Changes To Our Segment Performance Measure - Operating Income		0		0
Deferred income taxes			21,935	(21,419)
Legal Entity Restructuring
Segment Reporting Information
Deferred income taxes			49,000	49,000
Recasting of Intercompany Capital Lease
Segment Reporting Information
Changes To Our Segment Performance Measure - Revenues		0		0
Inter-company Revenues
Segment Reporting Information
Revenue from contracts with customers	(26,147)	(26,057)	(54,347)	(53,509)
Revenues	(35,688)	(35,175)	(73,559)	(71,751)
Consolidation, Eliminations
Segment Reporting Information
Revenue from contracts with customers	0	0	0	0
Corporate
Segment Reporting Information
Operating income	102	(836)	(405)	(2,531)
Changes To Our Segment Performance Measure - Operating Income		(200)		(300)
Electric Utilities
Segment Reporting Information
Revenue from contracts with customers	164,377	171,862	347,050	345,184
Revenues	166,354	173,616	349,281	347,171
Operating income	33,546	41,200	74,566	79,680
Changes To Our Segment Performance Measure - Operating Income		1,600		3,300
Gas Utilities
Segment Reporting Information
Revenue from contracts with customers	164,026	176,708	576,225	572,868
Revenues	165,469	177,620	576,549	574,964
Operating income	8,557	16,485	111,871	111,928
Power Generation
Segment Reporting Information
Revenue from contracts with customers	15,062	13,603	30,531	28,371
Revenues	24,708	22,744	49,953	46,682
Operating income	10,156	8,877	22,123	20,652
Changes To Our Segment Performance Measure - Operating Income		(1,400)		(3,000)
Power Generation \| Recasting of Intercompany Capital Lease
Segment Reporting Information
Changes To Our Segment Performance Measure - Revenues		900		1,700
Mining
Segment Reporting Information
Revenue from contracts with customers	12,428	16,345	28,257	32,902
Revenues	13,045	16,899	29,474	34,027
Operating income	1,640	3,825	5,977	8,096
Other Revenues
Segment Reporting Information
Revenues	4,142	3,243	3,982	5,277
Other Revenues \| Inter-company Revenues
Segment Reporting Information
Revenues	(9,541)	(9,118)	(19,212)	(18,242)
Other Revenues \| Consolidation, Eliminations
Segment Reporting Information
Revenues	0	0	0	0
Other Revenues \| Electric Utilities
Segment Reporting Information
Revenues	1,977	1,754	2,231	1,987
Other Revenues \| Gas Utilities
Segment Reporting Information
Revenues	1,443	912	324	2,096
Other Revenues \| Power Generation
Segment Reporting Information
Revenues	9,646	9,141	19,422	18,311
Other Revenues \| Mining
Segment Reporting Information
Revenues	617	554	1,217	1,125
External Operating Revenue
Segment Reporting Information
Revenue from contracts with customers	329,746	352,461	927,716	925,816
External Operating Revenue \| Electric Utilities
Segment Reporting Information
Revenue from contracts with customers	159,140	166,565	335,803	333,743
External Operating Revenue \| Gas Utilities
Segment Reporting Information
Revenue from contracts with customers	163,303	176,399	574,803	572,141
External Operating Revenue \| Power Generation
Segment Reporting Information
Revenue from contracts with customers	1,765	1,130	4,022	2,850
External Operating Revenue \| Mining
Segment Reporting Information
Revenue from contracts with customers	5,538	8,367	13,088	17,082
External Operating Revenue \| Other Revenues
Segment Reporting Information
Revenues	4,142	3,243	3,982	5,277
External Operating Revenue \| Other Revenues \| Electric Utilities
Segment Reporting Information
Revenues	1,977	1,754	2,231	1,987
External Operating Revenue \| Other Revenues \| Gas Utilities
Segment Reporting Information
Revenues	1,443	912	324	2,096
External Operating Revenue \| Other Revenues \| Power Generation
Segment Reporting Information
Revenues	434	348	870	718
External Operating Revenue \| Other Revenues \| Mining
Segment Reporting Information
Revenues	288	229	557	476
Inter-company Operating Revenue \| Electric Utilities
Segment Reporting Information
Revenue from contracts with customers	5,237	5,297	11,247	11,441
Inter-company Operating Revenue \| Gas Utilities
Segment Reporting Information
Revenue from contracts with customers	723	309	1,422	727
Inter-company Operating Revenue \| Power Generation
Segment Reporting Information
Revenue from contracts with customers	13,297	12,473	26,509	25,521
Inter-company Operating Revenue \| Mining
Segment Reporting Information
Revenue from contracts with customers	6,890	7,978	15,169	15,820
Inter-company Operating Revenue \| Other Revenues \| Electric Utilities
Segment Reporting Information
Revenues	0	0	0	0
Inter-company Operating Revenue \| Other Revenues \| Gas Utilities
Segment Reporting Information
Revenues	0	0	0	0
Inter-company Operating Revenue \| Other Revenues \| Power Generation
Segment Reporting Information
Revenues	9,212	8,793	18,552	17,593
Inter-company Operating Revenue \| Other Revenues \| Mining
Segment Reporting Information
Revenues	$ 329	$ 325	$ 660	$ 649

Business Segment Information: Segment and Corporate Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 7,081,453	$ 6,963,327
Changes To Our Segment Performance Measure - Assets	0
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	216,179	209,478
Electric Utilities
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,777,803	2,707,695
Gas Utilities
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,645,840	3,623,475
Power Generation
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	379,140	342,085
Mining
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 62,491	80,594
Recasting of Intercompany Capital Lease
Segment Reporting, Asset Reconciling Item [Line Items]
Changes To Our Segment Performance Measure - Assets		0
Recasting of Intercompany Capital Lease \| Electric Utilities
Segment Reporting, Asset Reconciling Item [Line Items]
Changes To Our Segment Performance Measure - Assets		(188,000)
Recasting of Intercompany Capital Lease \| Power Generation
Segment Reporting, Asset Reconciling Item [Line Items]
Changes To Our Segment Performance Measure - Assets		$ 188,000

Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts Receivable [Line Items]
Accounts Receivable, Trade	$ 116,273	$ 146,716
Unbilled Receivables, Current	55,326	125,646
Allowance for Doubtful Accounts	(5,086)	(3,209)
Accounts receivable, net	166,513	269,153
Corporate
Accounts Receivable [Line Items]
Accounts Receivable, Trade	3,233	5,008
Unbilled Receivables, Current	0	0
Allowance for Doubtful Accounts	(169)	(169)
Accounts receivable, net	3,064	4,839
Electric Utilities
Accounts Receivable [Line Items]
Accounts Receivable, Trade	39,982	39,721
Unbilled Receivables, Current	31,573	35,125
Allowance for Doubtful Accounts	(526)	(448)
Accounts receivable, net	71,029	74,398
Gas Utilities
Accounts Receivable [Line Items]
Accounts Receivable, Trade	67,686	96,123
Unbilled Receivables, Current	23,753	90,521
Allowance for Doubtful Accounts	(4,391)	(2,592)
Accounts receivable, net	87,048	184,052
Power Generation
Accounts Receivable [Line Items]
Accounts Receivable, Trade	2,867	1,876
Unbilled Receivables, Current	0	0
Allowance for Doubtful Accounts	0	0
Accounts receivable, net	2,867	1,876
Mining
Accounts Receivable [Line Items]
Accounts Receivable, Trade	2,505	3,988
Unbilled Receivables, Current	0	0
Allowance for Doubtful Accounts	0	0
Accounts receivable, net	$ 2,505	$ 3,988

Regulatory Accounting (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Regulatory assets
Regulatory assets	$ 283,049	$ 284,235
Less current regulatory assets	(48,925)	(48,776)
Regulatory assets, non-current	234,124	235,459
Regulatory liabilities
Regulatory liabilities	554,556	540,794
Less current regulatory liabilities	(39,642)	(29,810)
Regulatory liabilities, non-current	514,914	510,984
Deferred energy and gas costs
Regulatory liabilities
Regulatory liabilities	16,808	6,991
Employee benefit plans
Regulatory liabilities
Regulatory liabilities	41,814	42,533
Cost of removal
Regulatory liabilities
Regulatory liabilities	158,477	150,123
Excess deferred income taxes
Regulatory liabilities
Regulatory liabilities	307,871	310,562
TCJA revenue reduction
Regulatory liabilities
Regulatory liabilities	11,436	18,032
Other regulatory liabilities
Regulatory liabilities
Regulatory liabilities	18,150	12,553
Deferred energy and gas costs
Regulatory assets
Regulatory assets	34,257	29,661
Deferred gas cost adjustments
Regulatory assets
Regulatory assets	2,342	3,362
Gas price derivatives
Regulatory assets
Regulatory assets	3,945	6,201
Deferred taxes on AFUDC
Regulatory assets
Regulatory assets	7,716	7,841
Employee benefit plans
Regulatory assets
Regulatory assets	109,899	110,524
Environmental
Regulatory assets
Regulatory assets	931	959
Loss on reacquired debt
Regulatory assets
Regulatory assets	20,140	21,001
Renewable energy standard adjustment
Regulatory assets
Regulatory assets	1,994	1,722
Deferred taxes on flow through accounting
Regulatory assets
Regulatory assets	36,552	31,044
Decommissioning costs
Regulatory assets
Regulatory assets	11,518	11,700
Gas supply contract termination
Regulatory assets
Regulatory assets	11,413	14,310
Other regulatory assets
Regulatory assets
Regulatory assets	$ 42,342	$ 45,910

Regulatory Accounting: Rate Review (Details) $ in Millions				6 Months Ended
Regulatory Accounting: Rate Review (Details) $ in Millions	Jun. 25, 2019 USD ($)	Jun. 04, 2019 USD ($)	Feb. 01, 2019 USD ($) utility	Jun. 30, 2019 USD ($) utility MW	Jun. 13, 2019 utility	Mar. 29, 2019 utility
Wyoming Public Service Commission (WPSC) and South Dakota Public Utilities Commission (SDPUC) \| South Dakota Electric and Wyoming Electric \| Corriedale Wind Project
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Cost Of Plant Investment \| $				$ 57.0
Utility Plant, Megawatt Capacity \| MW				40
Public Utilities, Number of Electric Utilities Jointly Owning Wind Project				2
Kansas Corporation Commission \| Black Hills Energy, Kansas Gas
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount \| $	$ 1.4
Wyoming Public Service Commission (WPSC) \| Black Hills Energy, Wyoming Gas \| Rate Review Filed with the Regulatory Agency
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase, Amount \| $		$ 16.0
Public Utilities, Number of Companies Being Merged					4
Nebraska Public Service Commission (NPSC) \| Black Hills Energy, Nebraska Gas \| Application Filed
Public Utilities, General Disclosures [Line Items]
Public Utilities, Number of Companies Being Merged						2
Nebraska Public Service Commission (NPSC) \| Black Hills Energy, Nebraska Gas \| Rate Review Expected To Be Filed In The Next Fiscal Year
Public Utilities, General Disclosures [Line Items]
Public Utilities, Number of Companies Being Merged				2
Colorado Public Utilities Commission (CPUC) \| Black Hills Energy, Colorado Gas \| Rate Review Filed with the Regulatory Agency
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase, Amount \| $			$ 2.5
Public Utilities, Number of Companies Being Merged			2

Materials, Supplies and Fuel (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Inventory, Net [Abstract]
Materials and supplies	$ 80,639	$ 75,081
Fuel - Electric Utilities	2,350	2,850
Natural gas in storage held for distribution	19,841	39,368
Total materials, supplies and fuel	$ 102,830	$ 117,299

Earnings Per Share: Earnings Per Share Reconciliation (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 14,583	$ 21,917	$ 118,391	$ 154,921
Net income available for common stock	$ 14,583	$ 21,917	$ 118,391	$ 154,921
Weighted average shares - basic (in shares)	60,467	53,355	60,195	53,337
Dilutive effect of:
Equity Units (in shares)	0	1,057	0	904
Equity compensation (in shares)	139	108	138	120
Weighted average shares - diluted (in shares)	60,606	54,520	60,333	54,361

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Earnings Per Share: Anti-dilutive shares (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares	0	15	0	17
Equity compensation
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares	0	15	0	17

Notes Payable, Current Maturities and Debt: Schedule of Short-term Debt and Narrative (Details)	6 Months Ended
	Jun. 30, 2019 USD ($) credit_extension	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Short-term Debt [Line Items]
Notes payable	$ 102,500,000		$ 185,620,000
Letters of Credit	10,429,000		22,311,000
Commercial paper, maximum borrowing capacity	750,000,000
Net (payments) borrowings of short-term debt	(83,120,000)	$ (89,500,000)
Commercial Paper
Short-term Debt [Line Items]
Notes payable	$ 102,500,000		185,620,000
Debt instrument, term	397 days
Net (payments) borrowings of short-term debt	$ (83,000,000)
Short-term interest rate	2.60%
Revolving Credit Facility
Short-term Debt [Line Items]
Notes payable	$ 0		0
Letters of Credit	10,429,000		$ 22,311,000
Current borrowing capacity	$ 750,000,000
Number of one-year extension options \| credit_extension	2
Debt instrument, term	1 year
Maximum borrowing capacity	$ 1,000,000,000.0
Commitment fee	0.175%
Revolving Credit Facility \| Base Rate
Short-term Debt [Line Items]
Interest rate	0.125%
Revolving Credit Facility \| Eurodollar
Short-term Debt [Line Items]
Interest rate	1.125%
Revolving Credit Facility \| Letter of Credit
Short-term Debt [Line Items]
Interest rate	1.125%

Notes Payable, Current Maturities and Debt: Debt Covenants (Details)	Jun. 30, 2019
Maximum
Line of Credit Facility [Line Items]
Consolidated Indebtedness to Capitalization Ratio	0.65

Notes Payable, Current Maturities and Debt: Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 17, 2019	Jun. 30, 2019
Base Rate \| Corporate Term Loan Due June 2021
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		0.00%
Eurodollar \| Corporate Term Loan Due June 2021
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		0.70%
Black Hills Corporation \| London Interbank Offered Rate (LIBOR) \| Corporate \| Corporate Term Loan Due June 2021
Proceeds from Issuance of Debt	$ 400
Black Hills Corporation \| London Interbank Offered Rate (LIBOR) \| Corporate \| Corporate Term Loan Due July 2020
Extinguishment of Debt, Amount	$ 300

Equity: At-the-Market Equity Offering Program (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Aug. 04, 2017
At The Market Equity Offering Program Authorized Aggregate Value			$ 300.0
Payments of Stock Issuance Costs	$ 0.5	$ 0.7
Common Stock
At The Market Equity Offering Program Shares Issued	658,598	939,095
At The Market Equity Program Proceeds from Sale of Stock	$ 49.0	$ 69.0

Risk Management Activities: Utilities (Details) - Natural Gas, Distribution $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) MMBTU	Dec. 31, 2018 MMBTU
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months \| $	$ 0.4
Cash Flow Hedging
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	2,130,000
Natural gas futures purchased
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	2,480,000	4,000,000
Derivative, Remaining Maturity	18 months	24 months
Natural gas options purchased, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	2,160,000	4,320,000
Derivative, Remaining Maturity	9 months	13 months
Natural gas basis swaps purchased
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	2,360,000	3,960,000
Derivative, Remaining Maturity	18 months	24 months
Natural gas over-the-counter swaps, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	6,020,000	3,660,000
Derivative, Remaining Maturity	23 months	24 months
Credit Risk Derivative Liabilities, at Fair Value \| $	$ 0.5
Natural gas physical contracts, net
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,717,075	18,325,852
Derivative, Remaining Maturity	9 months	30 months

Risk Management Activities: Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative [Line Items]
Interest Costs Incurred	$ 36,058	$ 35,365	$ 72,032	$ 70,803
Cash Flow Hedging
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(630)	(876)	(789)	(2,210)
Cash Flow Hedging \| Designated as Hedging Instrument
Derivative [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	112	924	505	1,961
Cash Flow Hedging \| Interest rate swaps \| Designated as Hedging Instrument
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	713	713	1,426	1,426
Cash Flow Hedging \| Commodity Contract \| Designated as Hedging Instrument
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	(518)	48	(284)	(249)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(83)	163	(637)	784
Interest expense incurred net of amounts capitalized (including amortization of debt issuance costs, premiums and discounts) \| Cash Flow Hedging \| Interest rate swaps
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(713)	(713)	(1,426)	(1,426)
Cost of Sales \| Cash Flow Hedging \| Commodity Contract
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 83	$ (163)	$ 637	$ (784)

Risk Management Activities: Derivatives Not Designated as Hedge Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Regulatory assets	$ 283,049		$ 283,049		$ 284,235
Gas price derivatives
Derivative [Line Items]
Regulatory assets	3,945		3,945		$ 6,201
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,185)	$ 771	(1,160)	$ 1,025
Not Designated as Hedging Instrument \| Cost of Sales
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (1,185)	$ 771	$ (1,160)	$ 1,025

Fair Value Measurements: Schedule of Fair Values (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
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	$ (575)	$ (1,408)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(3,945)	(5,794)
Utilities Group
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	(575)	(1,408)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(3,945)	(5,794)
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	411	1,519
Derivative Liabilities, Total	1,622	1,007
Estimate of Fair Value Measurement \| Utilities Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	411	1,519
Derivative Liabilities, Fair Value Disclosure	1,622	1,007
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	0	0
Derivative Liabilities, Total	0	0
Fair Value, Inputs, Level 1 \| Utilities Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0
Derivative Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	986	2,927
Derivative Liabilities, Total	5,567	6,801
Fair Value, Inputs, Level 2 \| Utilities Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	986	2,927
Derivative Liabilities, Fair Value Disclosure	5,567	6,801
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	0	0
Derivative Liabilities, Total	0	0
Fair Value, Inputs, Level 3 \| Utilities Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Commodity Derivatives	0	0
Derivative Liabilities, Fair Value Disclosure	$ 0	$ 0

Fair Value Measurements: Balance Sheet Location (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Designated as Hedging Instrument
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	$ (503)	$ 315
Not Designated as Hedging Instrument
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	(708)	197
Commodity Contract \| Designated as Hedging Instrument \| Derivative assets — current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	415
Commodity Contract \| Designated as Hedging Instrument \| Other assets, non-current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	4	18
Commodity Contract \| Designated as Hedging Instrument \| Derivative liabilities — current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(449)	(114)
Commodity Contract \| Designated as Hedging Instrument \| Other deferred credits and other liabilities
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(58)	(4)
Commodity Contract \| Not Designated as Hedging Instrument \| Derivative assets — current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	405	1,085
Commodity Contract \| Not Designated as Hedging Instrument \| Other assets, non-current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2	1
Commodity Contract \| Not Designated as Hedging Instrument \| Derivative liabilities — current
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1,042)	(833)
Commodity Contract \| Not Designated as Hedging Instrument \| Other deferred credits and other liabilities
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (73)	$ (56)

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current maturities	$ 3,055,415	$ 2,956,578
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current maturities, Fair Value	$ 3,337,314	$ 3,039,108

Other Comprehensive Income (Loss): Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 20,000	$ 33,708	$ 144,625	$ 146,883
Income tax benefit (expense)	(2,307)	(6,541)	(19,570)	19,261
Net income	17,693	24,740	125,055	161,374
Operations and maintenance	124,931	118,282	248,844	234,378
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income	(631)	(1,131)	(908)	(2,619)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges \| Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(630)	(876)	(789)	(2,210)
Income tax benefit (expense)	153	197	188	494
Net income	(477)	(679)	(601)	(1,716)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) \| Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Operations and maintenance	20	44	39	89
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) \| Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Operations and maintenance	(221)	(622)	(441)	(1,244)
Accumulated Defined Benefit Plans Adjustment \| Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(201)	(578)	(402)	(1,155)
Income tax benefit (expense)	47	126	95	252
Net income	(154)	(452)	(307)	(903)
Cash Flow Hedging
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(630)	(876)	(789)	(2,210)
Interest Expense \| Cash Flow Hedging \| Interest rate swaps
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(713)	(713)	(1,426)	(1,426)
Cost of Sales \| Cash Flow Hedging \| Commodity Contract
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 83	$ (163)	$ 637	$ (784)

Other Comprehensive Income (Loss): Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (26,916)	$ (41,202)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(26,227)	(38,763)
Accumulated Defined Benefit Plans Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(9,937)	(21,103)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Reclassification from AOCI, Current Period, Tax		3
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(9,630)	(20,197)
Accumulated Defined Benefit Plans Adjustment \| Reclassification Out Of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	307	903
Accumulated Other Comprehensive Income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(219)	(198)
Reclassification from AOCI, Current Period, Tax		18
Accumulated Other Comprehensive Income (loss) \| Reclassification Out Of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	908	2,619
Interest Rate Swaps \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(17,307)	(19,581)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Reclassification from AOCI, Current Period, Tax		15
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(16,216)	(18,444)
Interest Rate Swaps \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent \| Reclassification Out Of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,091	1,122
Commodity Contract \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	328	(518)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(219)	(198)
Reclassification from AOCI, Current Period, Tax		0
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(381)	(122)
Commodity Contract \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent \| Reclassification Out Of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (490)	$ 594

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Non-cash Investing and Financing Activities from Continuing Operations [Abstract]
Property, plant and equipment acquired with accrued liabilities	$ 83,486	$ 37,168
Supplemental Cash Flow Elements [Abstract]
Interest (net of amounts capitalized)	(67,624)	(67,119)
Income taxes	$ 1,790	$ (14,837)

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Postretirement Benefits Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 454	$ 572	$ 908	$ 1,145
Interest cost	563	521	1,123	1,042
Expected return on plan assets	(58)	(56)	(115)	(113)
Prior service cost (benefit)	(100)	(99)	(199)	(198)
Net loss (gain)	0	54	0	108
Net periodic benefit cost	859	992	1,717	1,984
Payment for Pension and Other Postretirement Benefits [Abstract]
Contributions by Employer	1,108		2,217
Estimated Future Employer Contributions in Current Fiscal Year	2,217		2,217
Estimated Future Employer Contributions in Next Fiscal Year	4,271		4,271
Defined Benefit Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1,345	1,709	2,691	3,417
Interest cost	4,344	3,868	8,687	7,735
Expected return on plan assets	(6,100)	(6,185)	(12,200)	(12,370)
Prior service cost (benefit)	7	14	13	29
Net loss (gain)	940	2,157	1,881	4,315
Net periodic benefit cost	536	1,563	1,072	3,126
Payment for Pension and Other Postretirement Benefits [Abstract]
Contributions by Employer	0		0
Estimated Future Employer Contributions in Current Fiscal Year	12,700		12,700
Estimated Future Employer Contributions in Next Fiscal Year	12,700		12,700
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	692	435	1,977	715
Interest cost	324	292	648	585
Prior service cost (benefit)	1	1	1	1
Net loss (gain)	134	250	268	500
Net periodic benefit cost	1,151	$ 978	2,894	$ 1,801
Payment for Pension and Other Postretirement Benefits [Abstract]
Contributions by Employer	366		732
Estimated Future Employer Contributions in Current Fiscal Year	732		732
Estimated Future Employer Contributions in Next Fiscal Year	$ 1,562		$ 1,562

Commitments and Contingencies: Unconditional Purchase Obligations (Details) $ in Thousands	Jun. 30, 2019 USD ($) MW
Platte River Power Authority Wind Power Agreement
Unrecorded Unconditional Purchase Obligation [Line Items]
Utility Plant, Megawatt Capacity \| MW	60
Platte River Power Authority
Unrecorded Unconditional Purchase Obligation [Line Items]
Utility Plant, Megawatt Capacity \| MW	25
Platte River Power Authority \| Power Purchase Agreements
Unrecorded Unconditional Purchase Obligation [Line Items]
2019	$ 1,831
2020	5,490
2021	5,475
2022	5,475
2023	5,475
Thereafter	$ 2,729

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income tax benefit (expense)	$ (2,307)	$ (6,541)	$ (19,570)	$ 19,261
Deferred Income Tax (Expense) Benefit			21,935	(21,419)
Income tax (expense) benefit associated with changes in the prior estimated impact of tax reform on deferred income taxes			$ 1,700	$ (2,300)
Effective Tax Rate			13.50%	19.00%
Production tax credits			$ 3,500
Flow-through repairs deductions	$ 1,600		1,600
Legal Entity Restructuring
Deferred Income Tax (Expense) Benefit			$ 49,000	$ 49,000

Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued employee compensation, benefits and withholdings	$ 50,996	$ 63,742
Accrued property taxes	34,966	42,510
Customer deposits and prepayments	40,716	43,574
Accrued interest and contract adjustment payments	32,213	31,759
CIAC current portion	1,485	1,485
Other (none of which is individually significant)	28,141	32,431
Total accrued liabilities	$ 188,517	$ 215,501

Leases: Lessee (Details)	6 Months Ended
Leases: Lessee (Details)	Jun. 30, 2019
Minimum
Lessee, Lease, Description [Line Items]
Lessee - Lease Term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee - Lease Term	37 years

Leases: Lessee - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 385	$ 696
Amortization of right-of-use asset	27	44
Interest on lease liabilities	6	9
Total lease cost	$ 418	$ 749

Leases: Lessee - Supplemental Balance Sheet Information (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease assets	$ 5,161
Finance lease assets	521
Total lease assets	5,682
Operating lease liability, current	1,003
Finance lease liability, current	106
Operating lease liability, non-current	4,470
Finance lease liability, non-current	419
Total lease liabilities	$ 5,998

Leases: Lessee - Supplemental Cash Flow Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 528
Operating cash flows from finance lease	9
Financing cash flows from finance lease	40
Operating leases	2,738
Finance lease	$ 67

Leases: Lessee - Weighted Average Information (Details)	Jun. 30, 2019
Leases [Abstract]
Operating leases	8 years
Finance lease	5 years
Operating leases	4.25%
Finance lease	4.20%

Leases: Lessee - Future Minimum Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Operating Leases
2019	$ 705
2020	976
2021	858
2022	736
2023	708
Thereafter	2,654
Total lease payments	6,637
Less imputed interest	1,164
Present Value of Lease Liabilities - Operating leases	5,473
Finance Lease
2019	63
2020	126
2021	126
2022	126
2023	126
Thereafter	10
Total lease payments	577
Less imputed interest	52
Present value of lease liabilities - Finance Leases	525
Operating and Finance Lease Total
2019	768
2020	1,102
2021	984
2022	862
2023	834
Thereafter	2,664
Total lease payments	7,214
Less imputed interest	1,216
Present value of lease liabilities	$ 5,998
Prior Year End Operating Lease Future Minimum Payments
2019		$ 1,052
2020		464
2021		344
2022		224
2023		216
Thereafter		1,776
Total lease payments		$ 4,076

Leases: Lessor (Details) $ in Thousands	3 Months Ended	6 Months Ended
Leases: Lessor (Details) $ in Thousands	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lessor, Lease, Description [Line Items]
Operating lease income	$ 567	$ 1,205
Minimum
Lessor, Lease, Description [Line Items]
Lessor - Lease Term	1 year	1 year
Maximum
Lessor, Lease, Description [Line Items]
Lessor - Lease Term	35 years	35 years

Leases: Lessor - Future Minimum Payments (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Operating Leases
2019	$ 1,085
2020	2,010
2021	1,843
2022	1,793
2023	1,799
Thereafter	55,481
Total lease receivables	$ 64,011

Subsequent Event (Details)	Aug. 02, 2019 MW
Black Hills Wyoming and Wyoming Electric \| Federal Energy Regulatory Commission (FERC) \| Subsequent Event
Subsequent Event [Line Items]
Pending FERC Approval - Number of Megawatts Capacity to be Purchased and Delivered Through Intercompany Agreement	60