Black Hills (BKH) 10-Q 7 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Document Information [Line Items]
Entity Registrant Name	BLACK HILLS CORP /SD/
Entity Central Index Key	1,130,464
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		44,834,944
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No

Condensed Consolidated Statemen

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

Condensed Consolidated Stateme3

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

Condensed Consolidated Balance

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

Condensed Consolidated Balance5

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

Condensed Consolidated Stateme6

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

Management's Statement_

Management's Statement:	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Management's Statement	MANAGEMENT’S STATEMENT The unaudited Condensed Consolidated Financial Statements included herein have been prepared by Black Hills Corporation (together with our subsidiaries the “Company,” “us,” “we,” or “our”), pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to such rules and regulations; however, we believe that the footnotes adequately disclose the information presented. These Condensed Consolidated Financial Statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2014 Annual Report on Form 10-K/A filed with the SEC. We conduct our operations through the following reportable segments: Electric Utilities, Gas Utilities, Power Generation, Coal Mining and Oil and Gas. Our reportable segments are based on our method of internal reporting, which generally segregates the strategic business groups due to differences in products, services and regulation. All of our operations and assets are located within the United States. Accounting methods historically employed require certain estimates as of interim dates. The information furnished in the accompanying Condensed Consolidated Financial Statements reflects all adjustments, including accruals, which are, in the opinion of management, necessary for a fair presentation of the June 30, 2015 , December 31, 2014 , and June 30, 2014 financial information and are of a normal recurring nature. Certain industries in which we operate are highly seasonal, and revenue from, and certain expenses for, such operations may fluctuate significantly among quarterly periods. Demand for electricity and natural gas is sensitive to seasonal cooling, heating and industrial load requirements, as well as changes in market price. In particular, the normal peak usage season for electric utilities is June through August while the normal peak usage season for gas utilities is November through March. Significant earnings variances can be expected between the Gas Utilities segment’s peak and off-peak seasons. Due to this seasonal nature, our results of operations for the three and six months ended June 30, 2015 and June 30, 2014 , and our financial condition as of June 30, 2015 , December 31, 2014 , and June 30, 2014 , are not necessarily indicative of the results of operations and financial condition to be expected as of or for any other period. All earnings per share amounts discussed refer to diluted earnings per share unless otherwise noted. Recently Issued and Adopted Accounting Standards We have implemented all new accounting pronouncements that are in effect and may impact our financial statements. We are currently assessing the impact any other new accounting pronouncements that have been issued may have on our financial position, results of operations, or cash flows. Simplifying the Presentation of Debt Issuance Costs, ASU 2015-03 In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs. Debt issuance costs related to a recognized debt liability will be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts, rather than as an asset. Amortization of these costs will continue to be reported as interest expense. ASU 2015-03 is effective for annual and interim reporting periods beginning after December 15, 2015. Early adoption is permitted. We are currently evaluating the impact of adoption that ASU 2015-03 will have on our financial position, results of operations, or cash flows. Revenue from Contracts with Customers, ASU 2014-09 In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The standard provides companies with a single model for use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance, including industry-specific revenue guidance. The core principle of the model is to recognize revenue when control of the goods or services transfers to the customer, as opposed to recognizing revenue when the risks and rewards transfer to the customer under the existing revenue guidance. On July 9, 2015, FASB voted to defer the effective date of ASU 2014-09 by one year. The guidance would be effective for annual and interim reporting periods beginning after December 15, 2018 and early adoption is permitted. We are currently assessing the impact that adoption of ASU 2014-09 will have on our financial position, results of operations or cash flows. Correction of Immaterial Errors In preparing our condensed consolidated financial statements for the quarter ended June 30, 2015, we identified immaterial errors that impacted our previously issued consolidated financial statements. The prior period errors originated in the year ended December 31, 2008 and related to our oil and gas full cost ceiling impairment calculation to determine whether the net book value of the our oil and gas properties exceeded the ceiling. Specifically, the errors related to evaluating and correctly accounting for the treatment of tax related amounts associated with the calculation. The errors identified caused an understatement of 2008, 2009, 2012 and Q1 2015 noncash ceiling test impairment calculations, which resulted in an overstatement of depletion expense from 2009 through March 31, 2015, and an understatement of the 2012 gain on sale of oil and gas properties. In accordance with Staff Accounting Bulletin (SAB) No. 99, Materiality , and SAB No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements , we evaluated these errors, including both qualitative and quantitative considerations, and concluded that the errors did not, individually or in the aggregate, result in a material misstatement of our previously issued condensed consolidated financial statements. The following tables present the revisions to particular line items resulting from the corrections of these errors in this Quarterly Report on Form 10-Q. The impact of the errors relate entirely to our Oil and Gas segment. CONDENSED CONSOLIDATED STATEMENTS OF INCOME For the Three Months Ended June 30, 2014 For the Six Months Ended June 30, 2014 As Reported Adjustments As Revised As Reported Adjustments As Revised (in thousands expect per share amounts) Depreciation, depletion and amortization $ 36,712 $ (835 ) $ 35,877 $ 72,795 $ (1,669 ) $ 71,126 Total operating expenses $ 236,660 $ (835 ) $ 235,825 $ 607,231 $ (1,669 ) $ 605,562 Operating income (loss) $ 46,577 $ 835 $ 47,412 $ 136,175 $ 1,669 $ 137,844 Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes $ 30,471 $ 835 $ 31,306 $ 103,955 $ 1,669 $ 105,624 Income tax benefit (expense) $ (10,651 ) $ (308 ) $ (10,959 ) $ (36,017 ) $ (615 ) $ (36,632 ) Net income (loss) available for common stock $ 19,820 $ 527 $ 20,347 $ 67,938 $ 1,054 $ 68,992 Earnings (loss) per share of common stock: Earnings (loss) per share, Basic $ 0.45 $ 0.01 $ 0.46 $ 1.53 $ 0.03 $ 1.56 Earnings (loss) per share, Diluted $ 0.44 $ 0.02 $ 0.46 $ 1.52 $ 0.03 $ 1.55 CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) For the Three Months Ended June 30, 2014 For the Six Months Ended June 30, 2014 (in thousands) As Reported Adjustments As Revised As Reported Adjustments As Revised Net income (loss) available for common stock $ 19,820 $ 527 $ 20,347 $ 67,938 $ 1,054 $ 68,992 Comprehensive income (loss) $ 18,968 $ 527 $ 19,495 $ 65,919 $ 1,054 $ 66,973 CONDENSED CONSOLIDATED BALANCE SHEET As of June 30, 2014 As Reported Adjustments As Revised (in thousands) Accumulated depreciation and depletion $ (1,325,660 ) $ (35,573 ) $ (1,361,233 ) Total property, plant and equipment, net $ 3,082,631 $ (35,573 ) $ 3,047,058 TOTAL ASSETS $ 3,970,498 $ (35,573 ) $ 3,934,925 Deferred income tax liability, non-current $ 476,059 $ (12,379 ) $ 463,680 Total deferred credits and other liabilities $ 853,940 $ (12,379 ) $ 841,561 Retained earnings $ 573,379 $ (23,194 ) $ 550,185 Total stockholders' equity $ 1,341,325 $ (23,194 ) $ 1,318,131 TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY $ 3,970,498 $ (35,573 ) $ 3,934,925 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Six Months Ended June 30, 2014 As Reported Adjustments As Revised (in thousands) Net income (loss) available for common stock $ 67,938 $ 1,054 $ 68,992 Adjustments to reconcile net income (loss) to net cash provided by operating activities: Depreciation, depletion and amortization $ 72,795 $ (1,669 ) $ 71,126 Deferred income taxes $ 35,514 $ 615 $ 36,129 Net cash provided by (used in) operating activities $ 173,835 $ — $ 173,835 The Notes to the Condensed Consolidated Financial Statements have been revised to reflect the correction of these errors for all periods presented.

Subsequent Event_

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

Business Segment Information_

Business Segment Information:	6 Months Ended
	Jun. 30, 2015
Segment Reporting Information, Additional Information [Abstract]
Business Segment Information	BUSINESS SEGMENT INFORMATION Segment information and Corporate activities included in the accompanying Condensed Consolidated Statements of Income (Loss) were as follows (in thousands): Three Months Ended June 30, 2015 External Operating Revenue Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 169,751 $ 2,509 $ 17,702 Gas 79,426 — 3,165 Non-regulated Energy: Power Generation 1,706 20,603 7,549 Coal Mining 9,052 7,673 3,049 Oil and Gas (a)(b) 12,319 — (71,195 ) Corporate activities (c) — — (2,112 ) Inter-company eliminations — (30,785 ) — Total $ 272,254 $ — $ (41,842 ) Three Months Ended June 30, 2014 External Operating Revenue Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 158,740 $ 3,144 $ 11,427 Gas 102,499 — 1,994 Non-regulated Energy: Power Generation 1,267 20,713 7,194 Coal Mining 5,583 9,068 2,016 Oil and Gas 15,148 — (1,133 ) Corporate activities — — (1,151 ) Inter-company eliminations — (32,925 ) — Total $ 283,237 $ — $ 20,347 Six Months Ended June 30, 2015 External Operating Revenues Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 352,725 $ 5,933 $ 36,631 Gas 317,077 — 25,377 Non-regulated Energy: Power Generation 3,659 41,324 15,694 Coal Mining 17,194 15,465 6,059 Oil and Gas (a)(b) 23,586 — (90,310 ) Corporate activities (c) — — (1,443 ) Inter-company eliminations — (62,722 ) — Total $ 714,241 $ — $ (7,992 ) Six Months Ended June 30, 2014 External Operating Revenues Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 336,835 $ 7,151 $ 26,002 Gas 361,836 — 26,692 Non-regulated Energy: Power Generation 2,536 41,792 15,267 Coal Mining 12,201 17,948 4,480 Oil and Gas 29,998 — (2,628 ) Corporate activities — — (821 ) Inter-company eliminations — (66,891 ) — Total $ 743,406 $ — $ 68,992 __________ (a) Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million , respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (b) Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million . See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (c) Net income (loss) for the three and six months ended June 30, 2015 included acquisition costs, net of tax of $0.5 million and $0.3 million , respectively. See Note 2 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. Segment information and Corporate balances included in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands): Total Assets (net of inter-company eliminations) as of: June 30, 2015 December 31, 2014 June 30, 2014 Utilities: Electric (a) $ 2,856,903 $ 2,748,680 $ 2,603,900 Gas 801,295 906,922 799,365 Non-regulated Energy: Power Generation (a) 72,270 76,945 85,269 Coal Mining 76,079 74,407 73,701 Oil and Gas (b) (c) 275,068 332,343 272,264 Corporate activities 138,656 106,605 100,426 Total assets $ 4,220,271 $ 4,245,902 $ 3,934,925 __________ (a) The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease. (b) As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015 , respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (c) Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015 .

Accounts Receivable_

Accounts Receivable:	6 Months Ended
	Jun. 30, 2015
Receivables [Abstract]
Accounts Receivable	ACCOUNTS RECEIVABLE Following is a summary of Accounts receivable, net included in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: Accounts Unbilled Less Allowance for Accounts June 30, 2015 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 46,381 $ 33,501 $ (685 ) $ 79,197 Gas Utilities 25,635 9,418 (1,259 ) 33,794 Power Generation 1,199 — — 1,199 Coal Mining 3,402 — — 3,402 Oil and Gas 5,099 — (13 ) 5,086 Corporate 983 — — 983 Total $ 82,699 $ 42,919 $ (1,957 ) $ 123,661 Accounts Unbilled Less Allowance for Accounts December 31, 2014 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 59,714 $ 26,474 $ (722 ) $ 85,466 Gas Utilities 47,394 45,546 (781 ) 92,159 Power Generation 1,369 — — 1,369 Coal Mining 3,151 — — 3,151 Oil and Gas 5,305 — (13 ) 5,292 Corporate 2,555 — — 2,555 Total $ 119,488 $ 72,020 $ (1,516 ) $ 189,992 Accounts Unbilled Less Allowance for Accounts June 30, 2014 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 48,333 $ 21,716 $ (622 ) $ 69,427 Gas Utilities 43,104 9,265 (1,027 ) 51,342 Power Generation 1,388 — — 1,388 Coal Mining 1,866 — — 1,866 Oil and Gas 9,123 — (13 ) 9,110 Corporate 2,012 — — 2,012 Total $ 105,826 $ 30,981 $ (1,662 ) $ 135,145

Regulatory Accounting_

Regulatory Accounting:	6 Months Ended
	Jun. 30, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Accounting	REGULATORY ACCOUNTING We had the following regulatory assets and liabilities (in thousands): Maximum As of As of As of Amortization (in years) June 30, 2015 December 31, 2014 June 30, 2014 Regulatory assets Deferred energy and fuel cost adjustments - current (a) (d) 1 $ 26,862 $ 23,820 $ 29,605 Deferred gas cost adjustments (a)(d) 2 5,588 37,471 35,479 Gas price derivatives (a) 7 17,907 18,740 3,561 AFUDC (b) 45 12,321 12,358 12,468 Employee benefit plans (c) (e) 12 96,734 97,126 65,874 Environmental (a) subject to approval 1,224 1,314 1,314 Asset retirement obligations (a) 44 3,242 3,287 3,278 Bond issue cost (a) 23 3,204 3,276 3,347 Renewable energy standard adjustment (a) 5 5,629 9,622 14,501 Flow through accounting (c) 35 27,861 25,887 22,754 Decommissioning costs (f) 10 14,845 12,484 — Other regulatory assets (a) 15 12,555 12,454 10,780 $ 227,972 $ 257,839 $ 202,961 Regulatory liabilities Deferred energy and gas costs (a) (d) 1 $ 16,114 $ 6,496 $ 6,490 Employee benefit plans (c) (e) 12 53,163 53,139 34,356 Cost of removal (a) 44 84,118 78,249 70,841 Other regulatory liabilities (c) 25 8,350 10,947 8,603 $ 161,745 $ 148,831 $ 120,290 __________ (a) Recovery of costs, but we are not allowed a rate of return. (b) In addition to recovery of costs, we are allowed a rate of return. (c) In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively. (d) Our deferred energy, fuel cost, and gas cost adjustments represent the cost of electricity and gas delivered to our electric and gas utility customers that is either higher or lower than current rates and will be recovered or refunded in future rates. Fluctuations in deferred gas cost adjustments compared to the same period in the prior year are primarily due to higher natural gas prices driven by demand and market conditions from the peak winter heating season in the first part of 2014. Our electric and gas utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state utility commissions. (e) Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates. (f) Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

Materials, Supplies and Fuel_

Materials, Supplies and Fuel:	6 Months Ended
	Jun. 30, 2015
Inventory, Net [Abstract]
Materials, Supplies and Fuel	MATERIALS, SUPPLIES AND FUEL The following amounts by major classification are included in Materials, supplies and fuel in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Materials and supplies $ 54,646 $ 49,555 $ 51,925 Fuel - Electric Utilities 6,644 6,637 7,679 Natural gas in storage held for distribution 12,459 34,999 21,560 Total materials, supplies and fuel $ 73,749 $ 91,191 $ 81,164

Earnings Per Share_

Earnings Per Share:	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE A reconciliation of share amounts used to compute Earnings (loss) per share in the accompanying Condensed Consolidated Statements of Income (loss) was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Net income (loss) available for common stock $ (41,842 ) $ 20,347 $ (7,992 ) $ 68,992 Weighted average shares - basic 44,617 44,399 44,579 44,365 Dilutive effect of: Equity compensation — 189 — 206 Weighted average shares - diluted 44,617 44,588 44,579 44,571 The following outstanding securities were not included in the computation of diluted earnings per share as their effect would have been anti-dilutive. Due to our net loss the for the three and six months ended June 30, 2015 , potentially dilutive securities were excluded from the diluted loss per share calculation due to their anti-dilutive effect. In computing diluted net loss per share, 83,613 and 101,146 equity compensation shares were excluded from the computations for the three and six months ended June 30, 2015 , respectively. In addition to these potentially dilutive shares excluded due to our net loss for the three and six months ended June 30, 2015 , the following outstanding securities were also excluded in the computation of diluted net income (loss) per share as their inclusion would have been anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Equity compensation 119 81 113 63 Anti-dilutive shares 119 81 113 63

Notes Payable and Long-term Deb

Notes Payable and Long-term Debt:	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Notes Payable and Long-term debt	NOTES PAYABLE AND LONG-TERM DEBT We had the following short-term debt outstanding in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Balance Outstanding Letters of Credit Balance Outstanding Letters of Credit Balance Outstanding Letters of Credit Revolving Credit Facility $ 105,760 $ 23,100 $ 75,000 $ 35,000 $ 132,700 $ 20,272 Revolving Credit Facility On June 26, 2015, we amended our $500 million corporate Revolving Credit Facility agreement to extend the term through June 26, 2020 . This facility is similar to the former agreement, which includes an accordion feature that allows us, with the consent of the administrative agent and issuing agents, to increase the capacity of the facility to $750 million . Borrowings continue to be available under a base rate or various Eurodollar rate options. The interest costs associated with the letters of credit or borrowings and the commitment fee under the Revolving Credit Facility are determined based upon our most favorable Corporate credit rating from S&P and Moody’s for our unsecured debt. Based on our credit ratings, the margins for base rate borrowings, Eurodollar borrowings, and letters of credit were 0.125% , 1.125% , and 1.125% , respectively at June 30, 2015 . A commitment fee is charged on the unused amount of the Revolving Credit Facility and was 0.175% based on our credit rating. Replacement of Corporate Term Loan On April 13, 2015, we entered into a new $300 million Corporate term loan expiring April 12, 2017 . This new term loan replaced the $275 million Corporate term loan due on June 19, 2015 and was classified as Long-Term Debt as of June 30, 2015 . The additional $25 million , less interest and fees, was used for general corporate purposes. The cost of the borrowing under the new term loan is LIBOR plus a margin of 0.9% . The covenants on the new term loan are substantially the same as the Revolving Credit Facility. Debt Covenants Our Revolving Credit Facility and our Term Loan require compliance with the following financial covenant at the end of each quarter: As of June 30, 2015 Covenant Requirement Recourse Leverage Ratio 57% Less than 65% As of June 30, 2015 , we were in compliance with this covenant.

Risk Management Activities_

Risk Management Activities:	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities	RISK MANAGEMENT ACTIVITIES Our activities in the regulated and non-regulated energy sectors expose us to a number of risks in the normal operation of our businesses. Depending on the activity, we are exposed to varying degrees of market risk and credit risk. To manage and mitigate these identified risks, we have adopted the Black Hills Corporation Risk Policies and Procedures as discussed in our 2014 Annual Report on Form 10-K/A. Market Risk Market risk is the potential loss that might occur as a result of an adverse change in market price or rate. We are exposed to the following market risks including, but not limited to: • Commodity price risk associated with our natural long position in crude oil and natural gas reserves and production; and our fuel procurement for certain of our gas-fired generation assets; and • Interest rate risk associated with our variable-rate debt. Credit Risk Credit risk is the risk of financial loss resulting from non-performance of contractual obligations by a counterparty. For production and generation activities, we attempt to mitigate our credit exposure by conducting business primarily with high credit quality entities, setting tenor and credit limits commensurate with counterparty financial strength, obtaining master netting agreements, and mitigating credit exposure with less creditworthy counterparties through parental guarantees, prepayments, letters of credit, and other security agreements. We perform ongoing credit evaluations of our customers and adjust credit limits based upon payment history and the customer’s current creditworthiness, as determined by review of their current credit information. We maintain a provision for estimated credit losses based upon historical experience and any specific customer collection issue that is identified. Our derivative and hedging activities recorded in the accompanying Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Income (Loss) and Condensed Consolidated Statements of Comprehensive Income (Loss) are detailed below and in Note 10 . Oil and Gas We produce natural gas, NGLs and crude oil through our exploration and production activities. Our natural long positions, or unhedged open positions, result in commodity price risk and variability to our cash flows. To mitigate commodity price risk and preserve cash flows, we primarily use exchange traded futures and related options to hedge portions of our crude oil and natural gas production. We elect hedge accounting on these instruments. These transactions were designated at inception as cash flow hedges, documented under accounting standards for derivatives and hedging, and initially met prospective effectiveness testing. Effectiveness of our hedging position is evaluated at least quarterly. The derivatives were marked to fair value and were recorded as Derivative assets or Derivative liabilities on the accompanying Condensed Consolidated Balance Sheets, net of balance sheet offsetting as permitted by GAAP. The effective portion of the gain or loss on these derivatives for which we have elected cash flow hedge accounting is reported in AOCI in the accompanying Condensed Consolidated Balance Sheets and the ineffective portion, if any, is reported in Revenue in the accompanying Condensed Consolidated Statements of Income (Loss). The contract or notional amounts, terms of our commodity derivatives, and the derivative balances for our Oil and Gas segment reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Notional (a) 276,000 4,187,500 334,500 6,582,500 424,500 9,265,000 Maximum terms in months (b) 1 1 1 1 1 1 Derivative assets, current $ — $ — $ — $ — $ — $ — Derivative assets, non-current $ — $ — $ — $ — $ — $ — Derivative liabilities, current $ — $ — $ — $ — $ — $ — Derivative liabilities, non-current $ — $ — $ — $ — $ — $ — __________ (a) Crude oil in Bbls, natural gas in MMBtus. (b) Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument. Based on June 30, 2015 prices, a $6.4 million gain would be reclassified from AOCI over the next 12 months. Estimated and actual realized gains or losses will change during future periods as market prices fluctuate. Utilities The operations of our utilities, including natural gas sold by our Gas Utilities and natural gas used for Electric Utility generation plants or those plants under PPAs where our Electric Utilities must provide the generation fuel (tolling agreements), expose our utility customers to volatility in natural gas prices. Therefore, as allowed or required by state utility commissions, we have entered into commission approved hedging programs utilizing natural gas futures, options and basis swaps to reduce our customers’ underlying exposure to these fluctuations. These transactions are considered derivatives, and in accordance with accounting standards for derivatives and hedging, mark-to-market adjustments are recorded as Derivative assets or Derivative liabilities on the accompanying Condensed Consolidated Balance Sheets, net of balance sheet offsetting as permitted by GAAP. Unrealized and realized gains and losses, as well as option premiums and commissions on these transactions are recorded as Regulatory assets or Regulatory liabilities in the accompanying Condensed Consolidated Balance Sheets in accordance with state commission guidelines. When the related costs are recovered through our rates, the hedging activity is recognized in the Condensed Consolidated Statements of Income (Loss), or the Condensed Consolidated Statements of Comprehensive Income (Loss). The contract or notional amounts and terms of the natural gas derivative commodity instruments held at our Utilities were as follows, as of: June 30, 2015 December 31, 2014 June 30, 2014 Notional (MMBtus) Maximum Term (months) (a) Notional (MMBtus) Maximum Term (months) (a) Notional (MMBtus) Maximum Term (months) (a) Natural gas futures purchased 17,270,000 66 19,370,000 72 16,240,000 78 Natural gas options purchased 3,980,000 9 4,020,000 8 3,980,000 9 Natural gas basis swaps purchased 14,445,000 54 12,005,000 60 13,415,000 66 __________ (a) Term reflects the maximum forward period hedged. We had the following derivative balances related to the hedges in our Utilities reflected in our Condensed Consolidated Balance Sheets as of (in thousands): June 30, 2015 December 31, 2014 June 30, 2014 Derivative assets, current $ — $ — $ 1,737 Derivative assets, non-current $ — $ — $ — Derivative liabilities, non-current $ — $ — $ — Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities $ 17,907 $ 18,740 $ 3,561 Financing Activities We entered into floating-to-fixed interest rate swap agreements to reduce our exposure to interest rate fluctuations associated with our floating rate debt obligations. The contract or notional amounts, terms of our interest rate swaps and the interest rate swaps balances reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Interest Rate Swaps (a) Interest Rate Swaps (a) Interest Rate Swaps (a) Notional $ 75,000 $ 75,000 $ 75,000 Weighted average fixed interest rate 4.97 % 4.97 % 4.97 % Maximum terms in years 1.50 2.00 2.50 Derivative liabilities, current $ 3,289 $ 3,340 $ 3,480 Derivative liabilities, non-current $ 1,433 $ 2,680 $ 4,251 __________ (a) These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings. Based on June 30, 2015 market interest rates and balances related to our interest rate swaps, a loss of approximately $3.3 million would be realized, reported in pre-tax earnings and reclassified from AOCI during the next 12 months. Estimated and actual realized gains or losses will change during future periods as market interest rates change. Cash Flow Hedges The impacts of cash flow hedges on our Condensed Consolidated Statements of Income (Loss) were as follows (in thousands): Three Months Ended June 30, 2015 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (892 ) Interest expense $ (1,670 ) $ — Commodity derivatives (2,245 ) Revenue 3,666 — Total $ (3,137 ) $ 1,996 $ — Three Months Ended June 30, 2014 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (337 ) Interest expense $ (926 ) $ — Commodity derivatives (2,737 ) Revenue (1,251 ) — Total $ (3,074 ) $ (2,177 ) $ — Six Months Ended June 30, 2015 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (1,778 ) Interest expense $ (3,107 ) $ — Commodity derivatives 1,520 Revenue 7,598 — Total $ (258 ) $ 4,491 $ — Six Months Ended June 30, 2014 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (429 ) Interest expense $ (1,820 ) $ — Commodity derivatives (6,209 ) Revenue (1,562 ) — Total $ (6,638 ) $ (3,382 ) $ —

Fair Value Measurements_

Fair Value Measurements:	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Derivative Financial Instruments The accounting guidance for fair value measurements requires certain disclosures about assets and liabilities measured at fair value. This guidance establishes a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the placement within the fair value hierarchy levels. We record transfers, if necessary, between levels at the end of the reporting period for all of our financial instruments. For additional information see Notes 1, 8, 9 and 10 to the Consolidated Financial Statements included in our 2014 Annual Report on Form 10-K/A filed with the SEC. Transfers into Level 3, if any, occur when significant inputs used to value the derivative instruments become less observable such as a significant decrease in the frequency and volume in which the instrument is traded, negatively impacting the availability of observable pricing inputs. Transfers out of Level 3, if any, occur when the significant inputs become more observable, such as when the time between the valuation date and the delivery date of a transaction becomes shorter, positively impacting the availability of observable pricing inputs. Valuation Methodologies for Derivatives Oil and Gas Segment: • The commodity contracts for our Oil and Gas segment are valued using the market approach and include exchange-traded futures and basis swaps. Fair value was derived using exchange quoted settlement prices from third party brokers for similar instruments as to quantity and timing. The prices are then validated through third-party sources and therefore support Level 2 disclosure. Utilities Segments: • The commodity contracts for our Utilities Segments, valued using the market approach, include exchange-traded futures, options and basis swaps (Level 2) for natural gas contracts. For Level 2 assets and liabilities, fair value was derived using broker quotes validated by the exchange settlement pricing for the applicable contract. Corporate Activities: • The interest rate swaps are valued using the market approach. We establish fair value by obtaining price quotes directly from the counterparty which are based on the floating three-month LIBOR curve for the term of the contract. The fair value obtained from the counterparty is then validated by utilizing a nationally recognized service that obtains observable inputs to compute fair value for the same instrument. In addition, the fair value for the interest rate swap derivatives includes a CVA component. The CVA considers the fair value of the interest rate swap and the probability of default based on the life of the contract. For the probability of a default component, we utilize observable inputs supporting a Level 2 disclosure by using our credit default spread, if available, or a generic credit default spread curve that takes into account our credit ratings. Recurring Fair Value Measurements There have been no significant transfers between Level 1 and Level 2 derivative balances. Amounts included in cash collateral and counterparty netting in the following tables represent the impact of legally enforceable master netting agreements that allow us to settle positive and negative positions, netting of asset and liability positions permitted in accordance with accounting standards for offsetting as well as cash collateral posted with the same counterparties. The following tables set forth by level within the fair value hierarchy our gross assets and gross liabilities and related offsetting as permitted by GAAP that were accounted for at fair value on a recurring basis for derivative instruments. A discussion of fair value of financial instruments is included in Note 11 : As of June 30, 2015 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 5,178 — (5,178 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 4,372 — (4,372 ) — Commodity derivatives — Utilities — 2,577 — (2,577 ) — Total $ — $ 12,127 $ — $ (12,127 ) $ — Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 112 — (112 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 498 — (498 ) — Commodity derivatives — Utilities — 18,758 — (18,758 ) — Interest rate swaps — 4,722 — — 4,722 Total $ — $ 24,090 $ — $ (19,368 ) $ 4,722 As of December 31, 2014 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 8,599 — (8,599 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 6,558 — (6,558 ) — Commodity derivatives —Utilities — 2,389 — (2,389 ) — Total $ — $ 17,546 $ — $ (17,546 ) $ — Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — — — — — Options -- Gas — — — — — Basis Swaps -- Gas — 473 — (473 ) — Commodity derivatives — Utilities — 19,303 — (19,303 ) — Interest rate swaps — 6,020 — — 6,020 Total $ — $ 25,796 $ — $ (19,776 ) $ 6,020 As of June 30, 2014 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — — — — — Options -- Gas — — — — — Basis Swaps -- Gas — 600 — (600 ) — Commodity derivatives — Utilities — 4,342 — (2,605 ) 1,737 Total $ — $ 4,942 $ — $ (3,205 ) $ 1,737 Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 4,020 — (4,020 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 2,030 — (2,030 ) — Commodity derivatives — Utilities — 5,989 — (5,989 ) — Interest rate swaps — 7,731 — — 7,731 Total $ — $ 19,770 $ — $ (12,039 ) $ 7,731 Fair Value Measures by Balance Sheet Classification As required by accounting standards for derivatives and hedges, fair values within the following tables are presented on a gross basis aside from the netting of asset and liability positions permitted in accordance with accounting standards for offsetting and under terms of our master netting agreements and the impact of legally enforceable master netting agreements that allow us to settle positive and negative positions. However, the amounts do not include net cash collateral on deposit in margin accounts at June 30, 2015 , December 31, 2014 , and June 30, 2014 , to collateralize certain financial instruments, which are included in Derivative assets and/or Derivative liabilities. Therefore, the balances are not indicative of either our actual credit exposure or net economic exposure. Additionally, the amounts below will not agree with the amounts presented on our Condensed Consolidated Balance Sheets, nor will they correspond to the fair value measurements presented in Note 9 . The following tables present the fair value and balance sheet classification of our derivative instruments (in thousands): As of June 30, 2015 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 6,931 $ — Commodity derivatives Derivative assets — non-current 2,619 — Commodity derivatives Derivative liabilities — current — 493 Commodity derivatives Derivative liabilities — non-current — 117 Interest rate swaps Derivative liabilities — current — 3,289 Interest rate swaps Derivative liabilities — non-current — 1,433 Total derivatives designated as hedges $ 9,550 $ 5,332 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ — $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — 5,156 Commodity derivatives Derivative liabilities — non-current — 11,025 Total derivatives not designated as hedges $ — $ 16,181 As of December 31, 2014 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 10,391 $ — Commodity derivatives Derivative assets — non-current 4,766 — Commodity derivatives Derivative liabilities — current — 185 Commodity derivatives Derivative liabilities — non-current — 288 Interest rate swaps Derivative liabilities — current — 3,340 Interest rate swaps Derivative liabilities — non-current — 2,680 Total derivatives designated as hedges $ 15,157 $ 6,493 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ — $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — 8,032 Commodity derivatives Derivative liabilities — non-current — 8,882 Total derivatives not designated as hedges $ — $ 16,914 As of June 30, 2014 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 262 $ — Commodity derivatives Derivative assets — non-current 338 — Commodity derivatives Derivative liabilities — current — 3,702 Commodity derivatives Derivative liabilities — non-current — 2,348 Interest rate swaps Derivative liabilities — current — 3,480 Interest rate swaps Derivative liabilities — non-current — 4,251 Total derivatives designated as hedges $ 600 $ 13,781 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ 1,737 $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — — Commodity derivatives Derivative liabilities — non-current — 3,384 Total derivatives not designated as hedges $ 1,737 $ 3,384

Fair Value of Financial Instrum

Fair Value of Financial Instruments:	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS The estimated fair values of our financial instruments, excluding derivatives which are presented in Note 10 , were as follows (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Cash and cash equivalents (a) $ 87,210 $ 87,210 $ 21,218 $ 21,218 $ 14,697 $ 14,697 Restricted cash and equivalents (a) $ 2,316 $ 2,316 $ 2,056 $ 2,056 $ 2 $ 2 Notes payable (a) $ 105,760 $ 105,760 $ 75,000 $ 75,000 $ 132,700 $ 132,700 Long-term debt, including current maturities (b) $ 1,567,727 $ 1,700,487 $ 1,542,589 $ 1,734,555 $ 1,396,950 $ 1,578,756 __________ (a) Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy. (b) Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss):	6 Months Ended
	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss)	OTHER COMPREHENSIVE INCOME (LOSS) The components of the reclassification adjustments, net of tax, included in Other Comprehensive Income (Loss) for the periods were as follows (in thousands): Location on the Condensed Consolidated Statements of Income (Loss) Amount Reclassified from AOCI Three Months Ended Six Months Ended June 30, 2015 June 30, 2014 June 30, 2015 June 30, 2014 Gains (losses) on cash flow hedges: Interest rate swaps Interest expense $ 1,670 $ 926 $ 3,107 $ 1,820 Commodity contracts Revenue (3,666 ) 1,251 (7,598 ) 1,562 (1,996 ) 2,177 (4,491 ) 3,382 Income tax Income tax benefit (expense) 735 (774 ) 1,989 (1,199 ) Reclassification adjustments related to cash flow hedges, net of tax $ (1,261 ) $ 1,403 $ (2,502 ) $ 2,183 Amortization of defined benefit plans: Prior service cost Utilities - Operations and maintenance $ (26 ) $ (25 ) $ (53 ) $ (51 ) Non-regulated energy operations and maintenance (29 ) (84 ) (57 ) (71 ) Actuarial gain (loss) Utilities - Operations and maintenance 454 158 908 315 Non-regulated energy operations and maintenance 251 101 502 186 650 150 1,300 379 Income tax Income tax benefit (expense) (228 ) (52 ) (456 ) (133 ) Reclassification adjustments related to defined benefit plans, net of tax $ 422 $ 98 $ 844 $ 246 Balances by classification included within Accumulated other comprehensive income (loss) on the accompanying Condensed Consolidated Balance Sheets are as follows (in thousands): Derivatives Designated as Cash Flow Hedges Employee Benefit Plans Total Balance as of December 31, 2013 $ (7,133 ) $ (10,289 ) $ (17,422 ) Other comprehensive income (loss), net of tax (1,478 ) 311 (1,167 ) Balance as of March 31, 2014 (8,611 ) (9,978 ) (18,589 ) Other comprehensive income (loss), net of tax (556 ) (296 ) (852 ) Balance as of June 30, 2014 $ (9,167 ) $ (10,274 ) $ (19,441 ) Balance as of December 31, 2014 $ 5,093 $ (20,137 ) $ (15,044 ) Other comprehensive income (loss), net of tax 595 395 990 Balance as of March 31, 2015 5,688 (19,742 ) (14,054 ) Other comprehensive income (loss), net of tax 422 (3,227 ) (2,805 ) Balance as of June 30, 2015 $ 6,110 $ (22,969 ) $ (16,859 )

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information:	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information	SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION Six months ended June 30, 2015 June 30, 2014 (in thousands) Non-cash investing and financing activities from continuing operations— Property, plant and equipment acquired with accrued liabilities $ 36,661 $ 40,611 Increase (decrease) in capitalized assets associated with asset retirement obligations $ — $ (2,785 ) Cash (paid) refunded during the period for continuing operations— Interest (net of amounts capitalized) $ (37,698 ) $ (35,009 ) Income taxes, net $ (1,202 ) $ (396 )

Employee Benefit Plans_

Employee Benefit Plans:	6 Months Ended
	Jun. 30, 2015
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Defined Benefit Pension Plans The components of net periodic benefit cost for the Defined Benefit Pension Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 1,494 $ 1,362 $ 2,988 $ 2,724 Interest cost 3,880 3,963 7,760 7,926 Expected return on plan assets (4,867 ) (4,516 ) (9,734 ) (9,032 ) Prior service cost 15 16 30 32 Net loss (gain) 2,759 1,201 5,518 2,403 Net periodic benefit cost $ 3,281 $ 2,026 $ 6,562 $ 4,053 Defined Benefit Postretirement Healthcare Plans The components of net periodic benefit cost for the Defined Benefit Postretirement Healthcare Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 464 $ 425 $ 928 $ 850 Interest cost 450 480 900 959 Expected return on plan assets (33 ) (21 ) (66 ) (42 ) Prior service cost (benefit) (107 ) (107 ) (214 ) (214 ) Net loss (gain) 102 40 204 80 Net periodic benefit cost $ 876 $ 817 $ 1,752 $ 1,633 Supplemental Non-qualified Defined Benefit and Defined Contribution Plans The components of net periodic benefit cost for the Supplemental Non-qualified Defined Benefit and Defined Contribution Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 392 $ 374 $ 883 $ 749 Interest cost 364 362 728 724 Prior service cost 1 1 2 1 Net loss (gain) 270 124 540 249 Net periodic benefit cost $ 1,027 $ 861 $ 2,153 $ 1,723 Contributions We anticipate that we will make contributions to the benefit plans during 2015 and 2016 . Contributions to the Defined Benefit Pension Plans are cash contributions made directly to the Pension Plan Trust accounts. Contributions to the Healthcare and Supplemental Plan are made in the form of benefit payments. Contributions and anticipated contributions are as follows (in thousands): Contributions Made Contributions Made Additional Contributions Contributions Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Anticipated for 2015 Anticipated for 2016 Defined Benefit Pension Plans $ — $ — $ 10,200 $ 10,200 Non-pension Defined Benefit Postretirement Healthcare Plans $ 939 $ 1,878 $ 1,877 $ 4,026 Supplemental Non-qualified Defined Benefit and Defined Contribution Plans $ 372 $ 744 $ 743 $ 1,544

Commitments and Contingencies_

Commitments and Contingencies:	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES There have been no significant changes to commitments and contingencies from those previously disclosed in Note 18 of our Notes to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K/A except for those described below and in Note 2. Oil Creek Fire On June 29, 2012 , a forest and grassland fire occurred in the western Black Hills of Wyoming. A fire investigator retained by the Weston County Fire Protection District concluded that the fire was caused by the failure of a transmission structure owned, operated and maintained by Black Hills Power. On April 16, 2013, a large group of private landowners filed suit in the United States District Court for the District of Wyoming. There are approximately 36 Plaintiff groups (including property jointly owned by multiple family members or entities), or approximately 73 individually named private plaintiffs. In addition, the State of Wyoming has intervened in the lawsuit. Both the private landowners and the State of Wyoming assert claims for damages against Black Hills Power. The claims include allegations of negligence, negligence per se, common law nuisance and trespass. In addition to claims for compensatory damages, the lawsuit seeks recovery of punitive damages. We have denied and will vigorously defend all claims arising out of the fire. We cannot predict the outcome of expert investigation, the viability of alleged claims or the outcome of the litigation. Civil litigation of this kind, however, is likely to lead to settlement negotiations, including negotiations prompted by pre-trial civil court procedures. We believe such negotiations would effect a settlement of all claims. Regardless of whether the litigation is determined at trial or through settlement, we expect to incur significant investigation, legal and expert services expenses associated with the litigation. We maintain insurance coverage to limit our exposure to losses due to civil liability claims, and related litigation expense, and we will pursue recoveries to the maximum extent available under the policies. The deductible applicable to some types of claims arising out of this fire is $1.0 million . Based upon information currently available, we believe that a loss associated with settlement of pending claims is probable. Accordingly, we recorded a loss contingency liability related to these claims and we recorded a receivable for costs we believe are reimbursable and probable of recovery under our insurance coverage. Both of these entries reflect our reasonable estimate of probable future litigation expense and settlement costs; we did not base these contingencies on any determination that it is probable we would be found liable for these claims were they to be litigated. Given the uncertainty of litigation, however, a loss related to the fire, the litigation and related claims in excess of the loss we have determined to be probable is reasonably possible. We cannot reasonably estimate the amount of such possible loss because expert investigations and our review of damage claim documentation are ongoing, and there are significant factual and legal issues to be resolved. Further claims may be presented by these claimants and other parties. We have received claims seeking recovery for fire suppression, reclamation and rehabilitation costs, damage to fencing and other personal property, alleged injury to timber, grass or hay, livestock and related operations, and diminished value of real estate. Based on the legal standard for measuring damages that we believe applies to this matter, we estimate the current total claims to be approximately $55 million ; however the actual amount of allowed claims and any loss will depend on the resolution of certain factual and legal issues. We are not yet able to reasonably estimate the amount of any reasonable possible losses in excess of the amount we have accrued. Based upon information currently available, however, management does not expect the outcome of the claims to have a material adverse effect upon our consolidated financial condition, results of operations or cash flows. Dividend Restrictions Our Revolving Credit Facility and other debt obligations contain restrictions on the payment of cash dividends upon a default or event of default. As of June 30, 2015 , we were in compliance with the debt covenants. Due to our holding company structure, substantially all of our operating cash flows are provided by dividends paid or distributions made by our subsidiaries. The cash to pay dividends to our stockholders is derived from these cash flows. As a result, certain statutory limitations or regulatory or financing agreements could affect the levels of distributions allowed to be made by our subsidiaries. The following restrictions on distributions from our subsidiaries existed at June 30, 2015 : • Our utilities are generally limited to the amount of dividends allowed to be paid to us as a utility holding company under the Federal Power Act and settlement agreements with state regulatory jurisdictions. As of June 30, 2015 , the restricted net assets at our Utilities Group were approximately $325 million .

Impairment of Assets_

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

Management's Statement_ Correct

Management's Statement: Correction of Immaterial Errors (Tables)	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]	The impact of the errors relate entirely to our Oil and Gas segment. CONDENSED CONSOLIDATED STATEMENTS OF INCOME For the Three Months Ended June 30, 2014 For the Six Months Ended June 30, 2014 As Reported Adjustments As Revised As Reported Adjustments As Revised (in thousands expect per share amounts) Depreciation, depletion and amortization $ 36,712 $ (835 ) $ 35,877 $ 72,795 $ (1,669 ) $ 71,126 Total operating expenses $ 236,660 $ (835 ) $ 235,825 $ 607,231 $ (1,669 ) $ 605,562 Operating income (loss) $ 46,577 $ 835 $ 47,412 $ 136,175 $ 1,669 $ 137,844 Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes $ 30,471 $ 835 $ 31,306 $ 103,955 $ 1,669 $ 105,624 Income tax benefit (expense) $ (10,651 ) $ (308 ) $ (10,959 ) $ (36,017 ) $ (615 ) $ (36,632 ) Net income (loss) available for common stock $ 19,820 $ 527 $ 20,347 $ 67,938 $ 1,054 $ 68,992 Earnings (loss) per share of common stock: Earnings (loss) per share, Basic $ 0.45 $ 0.01 $ 0.46 $ 1.53 $ 0.03 $ 1.56 Earnings (loss) per share, Diluted $ 0.44 $ 0.02 $ 0.46 $ 1.52 $ 0.03 $ 1.55 CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) For the Three Months Ended June 30, 2014 For the Six Months Ended June 30, 2014 (in thousands) As Reported Adjustments As Revised As Reported Adjustments As Revised Net income (loss) available for common stock $ 19,820 $ 527 $ 20,347 $ 67,938 $ 1,054 $ 68,992 Comprehensive income (loss) $ 18,968 $ 527 $ 19,495 $ 65,919 $ 1,054 $ 66,973 CONDENSED CONSOLIDATED BALANCE SHEET As of June 30, 2014 As Reported Adjustments As Revised (in thousands) Accumulated depreciation and depletion $ (1,325,660 ) $ (35,573 ) $ (1,361,233 ) Total property, plant and equipment, net $ 3,082,631 $ (35,573 ) $ 3,047,058 TOTAL ASSETS $ 3,970,498 $ (35,573 ) $ 3,934,925 Deferred income tax liability, non-current $ 476,059 $ (12,379 ) $ 463,680 Total deferred credits and other liabilities $ 853,940 $ (12,379 ) $ 841,561 Retained earnings $ 573,379 $ (23,194 ) $ 550,185 Total stockholders' equity $ 1,341,325 $ (23,194 ) $ 1,318,131 TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY $ 3,970,498 $ (35,573 ) $ 3,934,925 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Six Months Ended June 30, 2014 As Reported Adjustments As Revised (in thousands) Net income (loss) available for common stock $ 67,938 $ 1,054 $ 68,992 Adjustments to reconcile net income (loss) to net cash provided by operating activities: Depreciation, depletion and amortization $ 72,795 $ (1,669 ) $ 71,126 Deferred income taxes $ 35,514 $ 615 $ 36,129 Net cash provided by (used in) operating activities $ 173,835 $ — $ 173,835 The Notes to the Condensed Consolidated Financial Statements have been revised to reflect the correction of these errors for all periods presented.

Business Segment Information_ B

Business Segment Information: Business Segment Information (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting Information, Additional Information [Abstract]
Schedule of Segment Reporting Information	Segment information and Corporate activities included in the accompanying Condensed Consolidated Statements of Income (Loss) were as follows (in thousands): Three Months Ended June 30, 2015 External Operating Revenue Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 169,751 $ 2,509 $ 17,702 Gas 79,426 — 3,165 Non-regulated Energy: Power Generation 1,706 20,603 7,549 Coal Mining 9,052 7,673 3,049 Oil and Gas (a)(b) 12,319 — (71,195 ) Corporate activities (c) — — (2,112 ) Inter-company eliminations — (30,785 ) — Total $ 272,254 $ — $ (41,842 ) Three Months Ended June 30, 2014 External Operating Revenue Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 158,740 $ 3,144 $ 11,427 Gas 102,499 — 1,994 Non-regulated Energy: Power Generation 1,267 20,713 7,194 Coal Mining 5,583 9,068 2,016 Oil and Gas 15,148 — (1,133 ) Corporate activities — — (1,151 ) Inter-company eliminations — (32,925 ) — Total $ 283,237 $ — $ 20,347 Six Months Ended June 30, 2015 External Operating Revenues Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 352,725 $ 5,933 $ 36,631 Gas 317,077 — 25,377 Non-regulated Energy: Power Generation 3,659 41,324 15,694 Coal Mining 17,194 15,465 6,059 Oil and Gas (a)(b) 23,586 — (90,310 ) Corporate activities (c) — — (1,443 ) Inter-company eliminations — (62,722 ) — Total $ 714,241 $ — $ (7,992 ) Six Months Ended June 30, 2014 External Operating Revenues Inter-company Operating Revenue Net Income (Loss) Utilities: Electric $ 336,835 $ 7,151 $ 26,002 Gas 361,836 — 26,692 Non-regulated Energy: Power Generation 2,536 41,792 15,267 Coal Mining 12,201 17,948 4,480 Oil and Gas 29,998 — (2,628 ) Corporate activities — — (821 ) Inter-company eliminations — (66,891 ) — Total $ 743,406 $ — $ 68,992 __________ (a) Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million , respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (b) Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million . See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (c) Net income (loss) for the three and six months ended June 30, 2015 included acquisition costs, net of tax of $0.5 million and $0.3 million , respectively. See Note 2 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
Reconciliation of Assets from Segment to Consolidated	Segment information and Corporate balances included in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands): Total Assets (net of inter-company eliminations) as of: June 30, 2015 December 31, 2014 June 30, 2014 Utilities: Electric (a) $ 2,856,903 $ 2,748,680 $ 2,603,900 Gas 801,295 906,922 799,365 Non-regulated Energy: Power Generation (a) 72,270 76,945 85,269 Coal Mining 76,079 74,407 73,701 Oil and Gas (b) (c) 275,068 332,343 272,264 Corporate activities 138,656 106,605 100,426 Total assets $ 4,220,271 $ 4,245,902 $ 3,934,925 __________ (a) The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease. (b) As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015 , respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q. (c) Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015 .

Accounts Receivable_ Accounts R

Accounts Receivable: Accounts Receivable (Tables)	6 Months Ended
	Jun. 30, 2015
Receivables [Abstract]
Accounts Receivable and Allowance for Doubtful Accounts	Following is a summary of Accounts receivable, net included in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: Accounts Unbilled Less Allowance for Accounts June 30, 2015 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 46,381 $ 33,501 $ (685 ) $ 79,197 Gas Utilities 25,635 9,418 (1,259 ) 33,794 Power Generation 1,199 — — 1,199 Coal Mining 3,402 — — 3,402 Oil and Gas 5,099 — (13 ) 5,086 Corporate 983 — — 983 Total $ 82,699 $ 42,919 $ (1,957 ) $ 123,661 Accounts Unbilled Less Allowance for Accounts December 31, 2014 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 59,714 $ 26,474 $ (722 ) $ 85,466 Gas Utilities 47,394 45,546 (781 ) 92,159 Power Generation 1,369 — — 1,369 Coal Mining 3,151 — — 3,151 Oil and Gas 5,305 — (13 ) 5,292 Corporate 2,555 — — 2,555 Total $ 119,488 $ 72,020 $ (1,516 ) $ 189,992 Accounts Unbilled Less Allowance for Accounts June 30, 2014 Receivable, Trade Revenue Doubtful Accounts Receivable, net Electric Utilities $ 48,333 $ 21,716 $ (622 ) $ 69,427 Gas Utilities 43,104 9,265 (1,027 ) 51,342 Power Generation 1,388 — — 1,388 Coal Mining 1,866 — — 1,866 Oil and Gas 9,123 — (13 ) 9,110 Corporate 2,012 — — 2,012 Total $ 105,826 $ 30,981 $ (1,662 ) $ 135,145

Regulatory Accounting_ Regulato

Regulatory Accounting: Regulatory Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets and Liabilities	We had the following regulatory assets and liabilities (in thousands): Maximum As of As of As of Amortization (in years) June 30, 2015 December 31, 2014 June 30, 2014 Regulatory assets Deferred energy and fuel cost adjustments - current (a) (d) 1 $ 26,862 $ 23,820 $ 29,605 Deferred gas cost adjustments (a)(d) 2 5,588 37,471 35,479 Gas price derivatives (a) 7 17,907 18,740 3,561 AFUDC (b) 45 12,321 12,358 12,468 Employee benefit plans (c) (e) 12 96,734 97,126 65,874 Environmental (a) subject to approval 1,224 1,314 1,314 Asset retirement obligations (a) 44 3,242 3,287 3,278 Bond issue cost (a) 23 3,204 3,276 3,347 Renewable energy standard adjustment (a) 5 5,629 9,622 14,501 Flow through accounting (c) 35 27,861 25,887 22,754 Decommissioning costs (f) 10 14,845 12,484 — Other regulatory assets (a) 15 12,555 12,454 10,780 $ 227,972 $ 257,839 $ 202,961 Regulatory liabilities Deferred energy and gas costs (a) (d) 1 $ 16,114 $ 6,496 $ 6,490 Employee benefit plans (c) (e) 12 53,163 53,139 34,356 Cost of removal (a) 44 84,118 78,249 70,841 Other regulatory liabilities (c) 25 8,350 10,947 8,603 $ 161,745 $ 148,831 $ 120,290 __________ (a) Recovery of costs, but we are not allowed a rate of return. (b) In addition to recovery of costs, we are allowed a rate of return. (c) In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively. (d) Our deferred energy, fuel cost, and gas cost adjustments represent the cost of electricity and gas delivered to our electric and gas utility customers that is either higher or lower than current rates and will be recovered or refunded in future rates. Fluctuations in deferred gas cost adjustments compared to the same period in the prior year are primarily due to higher natural gas prices driven by demand and market conditions from the peak winter heating season in the first part of 2014. Our electric and gas utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state utility commissions. (e) Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates. (f) Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

Materials, Supplies and Fuel_ M

Materials, Supplies and Fuel: Materials, Supplies and Fuel (Tables)	6 Months Ended
	Jun. 30, 2015
Inventory, Net [Abstract]
Materials, Supplies and Fuel	The following amounts by major classification are included in Materials, supplies and fuel in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Materials and supplies $ 54,646 $ 49,555 $ 51,925 Fuel - Electric Utilities 6,644 6,637 7,679 Natural gas in storage held for distribution 12,459 34,999 21,560 Total materials, supplies and fuel $ 73,749 $ 91,191 $ 81,164

Earnings Per Share_ Earnings Pe

Earnings Per Share: Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share Reconciliation	A reconciliation of share amounts used to compute Earnings (loss) per share in the accompanying Condensed Consolidated Statements of Income (loss) was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Net income (loss) available for common stock $ (41,842 ) $ 20,347 $ (7,992 ) $ 68,992 Weighted average shares - basic 44,617 44,399 44,579 44,365 Dilutive effect of: Equity compensation — 189 — 206 Weighted average shares - diluted 44,617 44,588 44,579 44,571
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	In addition to these potentially dilutive shares excluded due to our net loss for the three and six months ended June 30, 2015 , the following outstanding securities were also excluded in the computation of diluted net income (loss) per share as their inclusion would have been anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Equity compensation 119 81 113 63 Anti-dilutive shares 119 81 113 63

Notes Payable and Long-term D29

Notes Payable and Long-term Debt: Notes Payable and Long-term Debt (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Schedule of Short-term Debt	We had the following short-term debt outstanding in the accompanying Condensed Consolidated Balance Sheets (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Balance Outstanding Letters of Credit Balance Outstanding Letters of Credit Balance Outstanding Letters of Credit Revolving Credit Facility $ 105,760 $ 23,100 $ 75,000 $ 35,000 $ 132,700 $ 20,272
Schedule of Credit Facility Covenants	Our Revolving Credit Facility and our Term Loan require compliance with the following financial covenant at the end of each quarter: As of June 30, 2015 Covenant Requirement Recourse Leverage Ratio 57% Less than 65%

Risk Management Activities_ Ris

Risk Management Activities: Risk Management Activities (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative [Line Items]
Schedule of Derivative Instruments	The contract or notional amounts, terms of our interest rate swaps and the interest rate swaps balances reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Interest Rate Swaps (a) Interest Rate Swaps (a) Interest Rate Swaps (a) Notional $ 75,000 $ 75,000 $ 75,000 Weighted average fixed interest rate 4.97 % 4.97 % 4.97 % Maximum terms in years 1.50 2.00 2.50 Derivative liabilities, current $ 3,289 $ 3,340 $ 3,480 Derivative liabilities, non-current $ 1,433 $ 2,680 $ 4,251 __________ (a) These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings.
Derivative Instruments, Gain (Loss)	The impacts of cash flow hedges on our Condensed Consolidated Statements of Income (Loss) were as follows (in thousands): Three Months Ended June 30, 2015 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (892 ) Interest expense $ (1,670 ) $ — Commodity derivatives (2,245 ) Revenue 3,666 — Total $ (3,137 ) $ 1,996 $ — Three Months Ended June 30, 2014 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (337 ) Interest expense $ (926 ) $ — Commodity derivatives (2,737 ) Revenue (1,251 ) — Total $ (3,074 ) $ (2,177 ) $ — Six Months Ended June 30, 2015 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (1,778 ) Interest expense $ (3,107 ) $ — Commodity derivatives 1,520 Revenue 7,598 — Total $ (258 ) $ 4,491 $ — Six Months Ended June 30, 2014 Derivatives in Cash Flow Hedging Relationships Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion) Location of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion) Location of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion) Interest rate swaps $ (429 ) Interest expense $ (1,820 ) $ — Commodity derivatives (6,209 ) Revenue (1,562 ) — Total $ (6,638 ) $ (3,382 ) $ —
Oil and Gas [Member]
Derivative [Line Items]
Schedule of Derivative Instruments	The contract or notional amounts, terms of our commodity derivatives, and the derivative balances for our Oil and Gas segment reflected on the Condensed Consolidated Balance Sheets were as follows (dollars in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Crude Oil Futures, Swaps and Options Natural Gas Futures and Swaps Notional (a) 276,000 4,187,500 334,500 6,582,500 424,500 9,265,000 Maximum terms in months (b) 1 1 1 1 1 1 Derivative assets, current $ — $ — $ — $ — $ — $ — Derivative assets, non-current $ — $ — $ — $ — $ — $ — Derivative liabilities, current $ — $ — $ — $ — $ — $ — Derivative liabilities, non-current $ — $ — $ — $ — $ — $ — __________ (a) Crude oil in Bbls, natural gas in MMBtus. (b) Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument.
Utilities Group [Member]
Derivative [Line Items]
Schedule of Derivative Instruments	We had the following derivative balances related to the hedges in our Utilities reflected in our Condensed Consolidated Balance Sheets as of (in thousands): June 30, 2015 December 31, 2014 June 30, 2014 Derivative assets, current $ — $ — $ 1,737 Derivative assets, non-current $ — $ — $ — Derivative liabilities, non-current $ — $ — $ — Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities $ 17,907 $ 18,740 $ 3,561
Contract or Notional Amounts and Terms of Commodity Derivatives	The contract or notional amounts and terms of the natural gas derivative commodity instruments held at our Utilities were as follows, as of: June 30, 2015 December 31, 2014 June 30, 2014 Notional (MMBtus) Maximum Term (months) (a) Notional (MMBtus) Maximum Term (months) (a) Notional (MMBtus) Maximum Term (months) (a) Natural gas futures purchased 17,270,000 66 19,370,000 72 16,240,000 78 Natural gas options purchased 3,980,000 9 4,020,000 8 3,980,000 9 Natural gas basis swaps purchased 14,445,000 54 12,005,000 60 13,415,000 66 __________ (a) Term reflects the maximum forward period hedged.

Fair Value Measurements_ Fair V

Fair Value Measurements: Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value Hierarchy, Measured on Recurring Basis	The following tables set forth by level within the fair value hierarchy our gross assets and gross liabilities and related offsetting as permitted by GAAP that were accounted for at fair value on a recurring basis for derivative instruments. A discussion of fair value of financial instruments is included in Note 11 : As of June 30, 2015 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 5,178 — (5,178 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 4,372 — (4,372 ) — Commodity derivatives — Utilities — 2,577 — (2,577 ) — Total $ — $ 12,127 $ — $ (12,127 ) $ — Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 112 — (112 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 498 — (498 ) — Commodity derivatives — Utilities — 18,758 — (18,758 ) — Interest rate swaps — 4,722 — — 4,722 Total $ — $ 24,090 $ — $ (19,368 ) $ 4,722 As of December 31, 2014 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 8,599 — (8,599 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 6,558 — (6,558 ) — Commodity derivatives —Utilities — 2,389 — (2,389 ) — Total $ — $ 17,546 $ — $ (17,546 ) $ — Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — — — — — Options -- Gas — — — — — Basis Swaps -- Gas — 473 — (473 ) — Commodity derivatives — Utilities — 19,303 — (19,303 ) — Interest rate swaps — 6,020 — — 6,020 Total $ — $ 25,796 $ — $ (19,776 ) $ 6,020 As of June 30, 2014 Level 1 Level 2 Level 3 Cash Collateral and Counterparty Netting Total (in thousands) Assets: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — — — — — Options -- Gas — — — — — Basis Swaps -- Gas — 600 — (600 ) — Commodity derivatives — Utilities — 4,342 — (2,605 ) 1,737 Total $ — $ 4,942 $ — $ (3,205 ) $ 1,737 Liabilities: Commodity derivatives — Oil and Gas Options -- Oil $ — $ — $ — $ — $ — Basis Swaps -- Oil — 4,020 — (4,020 ) — Options -- Gas — — — — — Basis Swaps -- Gas — 2,030 — (2,030 ) — Commodity derivatives — Utilities — 5,989 — (5,989 ) — Interest rate swaps — 7,731 — — 7,731 Total $ — $ 19,770 $ — $ (12,039 ) $ 7,731
Schedule of Derivative Instruments Balance Sheet Location	The following tables present the fair value and balance sheet classification of our derivative instruments (in thousands): As of June 30, 2015 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 6,931 $ — Commodity derivatives Derivative assets — non-current 2,619 — Commodity derivatives Derivative liabilities — current — 493 Commodity derivatives Derivative liabilities — non-current — 117 Interest rate swaps Derivative liabilities — current — 3,289 Interest rate swaps Derivative liabilities — non-current — 1,433 Total derivatives designated as hedges $ 9,550 $ 5,332 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ — $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — 5,156 Commodity derivatives Derivative liabilities — non-current — 11,025 Total derivatives not designated as hedges $ — $ 16,181 As of December 31, 2014 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 10,391 $ — Commodity derivatives Derivative assets — non-current 4,766 — Commodity derivatives Derivative liabilities — current — 185 Commodity derivatives Derivative liabilities — non-current — 288 Interest rate swaps Derivative liabilities — current — 3,340 Interest rate swaps Derivative liabilities — non-current — 2,680 Total derivatives designated as hedges $ 15,157 $ 6,493 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ — $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — 8,032 Commodity derivatives Derivative liabilities — non-current — 8,882 Total derivatives not designated as hedges $ — $ 16,914 As of June 30, 2014 Balance Sheet Location Fair Value of Asset Derivatives Fair Value of Liability Derivatives Derivatives designated as hedges: Commodity derivatives Derivative assets — current $ 262 $ — Commodity derivatives Derivative assets — non-current 338 — Commodity derivatives Derivative liabilities — current — 3,702 Commodity derivatives Derivative liabilities — non-current — 2,348 Interest rate swaps Derivative liabilities — current — 3,480 Interest rate swaps Derivative liabilities — non-current — 4,251 Total derivatives designated as hedges $ 600 $ 13,781 Derivatives not designated as hedges: Commodity derivatives Derivative assets — current $ 1,737 $ — Commodity derivatives Derivative assets — non-current — — Commodity derivatives Derivative liabilities — current — — Commodity derivatives Derivative liabilities — non-current — 3,384 Total derivatives not designated as hedges $ 1,737 $ 3,384

Fair Value of Financial Instr32

Fair Value of Financial Instruments: Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	The estimated fair values of our financial instruments, excluding derivatives which are presented in Note 10 , were as follows (in thousands) as of: June 30, 2015 December 31, 2014 June 30, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value Cash and cash equivalents (a) $ 87,210 $ 87,210 $ 21,218 $ 21,218 $ 14,697 $ 14,697 Restricted cash and equivalents (a) $ 2,316 $ 2,316 $ 2,056 $ 2,056 $ 2 $ 2 Notes payable (a) $ 105,760 $ 105,760 $ 75,000 $ 75,000 $ 132,700 $ 132,700 Long-term debt, including current maturities (b) $ 1,567,727 $ 1,700,487 $ 1,542,589 $ 1,734,555 $ 1,396,950 $ 1,578,756 __________ (a) Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy. (b) Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

Other Comprehensive Income (L33

Other Comprehensive Income (Loss): Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Reclassification Out of Accumulated Other Comprehensive Income (Loss)	The components of the reclassification adjustments, net of tax, included in Other Comprehensive Income (Loss) for the periods were as follows (in thousands): Location on the Condensed Consolidated Statements of Income (Loss) Amount Reclassified from AOCI Three Months Ended Six Months Ended June 30, 2015 June 30, 2014 June 30, 2015 June 30, 2014 Gains (losses) on cash flow hedges: Interest rate swaps Interest expense $ 1,670 $ 926 $ 3,107 $ 1,820 Commodity contracts Revenue (3,666 ) 1,251 (7,598 ) 1,562 (1,996 ) 2,177 (4,491 ) 3,382 Income tax Income tax benefit (expense) 735 (774 ) 1,989 (1,199 ) Reclassification adjustments related to cash flow hedges, net of tax $ (1,261 ) $ 1,403 $ (2,502 ) $ 2,183 Amortization of defined benefit plans: Prior service cost Utilities - Operations and maintenance $ (26 ) $ (25 ) $ (53 ) $ (51 ) Non-regulated energy operations and maintenance (29 ) (84 ) (57 ) (71 ) Actuarial gain (loss) Utilities - Operations and maintenance 454 158 908 315 Non-regulated energy operations and maintenance 251 101 502 186 650 150 1,300 379 Income tax Income tax benefit (expense) (228 ) (52 ) (456 ) (133 ) Reclassification adjustments related to defined benefit plans, net of tax $ 422 $ 98 $ 844 $ 246
Schedule of Accumulated Other Comprehensive Income (Loss)	Balances by classification included within Accumulated other comprehensive income (loss) on the accompanying Condensed Consolidated Balance Sheets are as follows (in thousands): Derivatives Designated as Cash Flow Hedges Employee Benefit Plans Total Balance as of December 31, 2013 $ (7,133 ) $ (10,289 ) $ (17,422 ) Other comprehensive income (loss), net of tax (1,478 ) 311 (1,167 ) Balance as of March 31, 2014 (8,611 ) (9,978 ) (18,589 ) Other comprehensive income (loss), net of tax (556 ) (296 ) (852 ) Balance as of June 30, 2014 $ (9,167 ) $ (10,274 ) $ (19,441 ) Balance as of December 31, 2014 $ 5,093 $ (20,137 ) $ (15,044 ) Other comprehensive income (loss), net of tax 595 395 990 Balance as of March 31, 2015 5,688 (19,742 ) (14,054 ) Other comprehensive income (loss), net of tax 422 (3,227 ) (2,805 ) Balance as of June 30, 2015 $ 6,110 $ (22,969 ) $ (16,859 )

Supplemental Disclosure of Ca34

Supplemental Disclosure of Cash Flow Information: Supplemental Disclosure of Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information	Six months ended June 30, 2015 June 30, 2014 (in thousands) Non-cash investing and financing activities from continuing operations— Property, plant and equipment acquired with accrued liabilities $ 36,661 $ 40,611 Increase (decrease) in capitalized assets associated with asset retirement obligations $ — $ (2,785 ) Cash (paid) refunded during the period for continuing operations— Interest (net of amounts capitalized) $ (37,698 ) $ (35,009 ) Income taxes, net $ (1,202 ) $ (396 )

Employee Benefit Plans_ Employe

Employee Benefit Plans: Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2015
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Schedule of Net Benefit Costs	The components of net periodic benefit cost for the Defined Benefit Pension Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 1,494 $ 1,362 $ 2,988 $ 2,724 Interest cost 3,880 3,963 7,760 7,926 Expected return on plan assets (4,867 ) (4,516 ) (9,734 ) (9,032 ) Prior service cost 15 16 30 32 Net loss (gain) 2,759 1,201 5,518 2,403 Net periodic benefit cost $ 3,281 $ 2,026 $ 6,562 $ 4,053 Defined Benefit Postretirement Healthcare Plans The components of net periodic benefit cost for the Defined Benefit Postretirement Healthcare Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 464 $ 425 $ 928 $ 850 Interest cost 450 480 900 959 Expected return on plan assets (33 ) (21 ) (66 ) (42 ) Prior service cost (benefit) (107 ) (107 ) (214 ) (214 ) Net loss (gain) 102 40 204 80 Net periodic benefit cost $ 876 $ 817 $ 1,752 $ 1,633 Supplemental Non-qualified Defined Benefit and Defined Contribution Plans The components of net periodic benefit cost for the Supplemental Non-qualified Defined Benefit and Defined Contribution Plans were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Service cost $ 392 $ 374 $ 883 $ 749 Interest cost 364 362 728 724 Prior service cost 1 1 2 1 Net loss (gain) 270 124 540 249 Net periodic benefit cost $ 1,027 $ 861 $ 2,153 $ 1,723
Schedule of Defined Benefit Plans Contributions	Contributions and anticipated contributions are as follows (in thousands): Contributions Made Contributions Made Additional Contributions Contributions Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Anticipated for 2015 Anticipated for 2016 Defined Benefit Pension Plans $ — $ — $ 10,200 $ 10,200 Non-pension Defined Benefit Postretirement Healthcare Plans $ 939 $ 1,878 $ 1,877 $ 4,026 Supplemental Non-qualified Defined Benefit and Defined Contribution Plans $ 372 $ 744 $ 743 $ 1,544

Management's Statement_ Corre36

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

Subsequent Event_ Subsequent Ev

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

Business Segment Information_ I

Business Segment Information: Information Relating to Segment Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Segment Reporting Information
Non-cash impairment of our Oil and Gas equity investments	$ 5,170		$ 0	$ 5,170		$ 0
Revenue	272,254		283,237	714,241		743,406
Net Income (Loss)	(41,842)		20,347	(7,992)		68,992
Inter-company eliminations [Member]
Segment Reporting Information
Revenue	(30,785)		(32,925)	(62,722)		(66,891)
Net Income (Loss)	0		0	0		0
Corporate activities[Member]
Segment Reporting Information
Revenue	0		0	0		0
Net Income (Loss)	(2,112)	[1]	(1,151)	(1,443)	[1]	(821)
Consolidation, Eliminations [Member]
Segment Reporting Information
Revenue	0		0	0		0
Electric Utilities [Member]
Segment Reporting Information
Revenue	169,751		158,740	352,725		336,835
Net Income (Loss)	17,702		11,427	36,631		26,002
Electric Utilities [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	2,509		3,144	5,933		7,151
Gas Utilities [Member]
Segment Reporting Information
Revenue	79,426		102,499	317,077		361,836
Net Income (Loss)	3,165		1,994	25,377		26,692
Gas Utilities [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	0		0	0		0
Power Generation [Member]
Segment Reporting Information
Revenue	1,706		1,267	3,659		2,536
Net Income (Loss)	7,549		7,194	15,694		15,267
Power Generation [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	20,603		20,713	41,324		41,792
Coal Mining [Member]
Segment Reporting Information
Revenue	9,052		5,583	17,194		12,201
Net Income (Loss)	3,049		2,016	6,059		4,480
Coal Mining [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	7,673		9,068	15,465		17,948
Oil and Gas [Member]
Segment Reporting Information
Non-cash impairment of our Oil and Gas equity investments				5,170
Revenue	12,319		15,148	23,586		29,998
Net Income (Loss)	(71,195)	[2],[3]	(1,133)	(90,310)	[2],[3]	(2,628)
Impairment of Oil and Gas Properties Net of Tax	77,000			63,000
Equity Method Investment, Other than Temporary Impairment, Net of Income Taxes	3,400
Oil and Gas [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	0		$ 0	0		$ 0
Net of Tax [Member] | Corporate activities[Member]
Segment Reporting Information
Business Acquisition, Transaction Costs	$ 500			$ 300
[1]	Net income (loss) for the three and six months ended June 30, 2015 included acquisition costs, net of tax of $0.5 million and $0.3 million, respectively. See Note 2 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[2]	Net income (loss) for the three and six months ended June 30, 2015 included a non-cash after-tax impairment to equity investments of $3.4 million. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[3]	Net income (loss) for the three and six months ended June 30, 2015 included non-cash after-tax ceiling test impairments of $63 million and $77 million, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.

Business Segment Information_ S

Business Segment Information: Segment and Corporate Assets (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		$ 4,220,271			$ 3,934,925	$ 4,220,271		$ 3,934,925	$ 4,245,902
Impairment of Oil and Gas Properties						121,690		0
Non-cash impairment of our Oil and Gas equity investments		5,170			0	5,170		0
Corporate activities[Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		138,656			100,426	138,656		100,426	106,605
Electric Utilities [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	2,856,903			2,603,900	2,856,903		2,603,900	2,748,680
Gas Utilities [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		801,295			799,365	801,295		799,365	906,922
Power Generation [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	72,270			85,269	72,270		85,269	76,945
Coal Mining [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		76,079			73,701	76,079		73,701	74,407
Oil and Gas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		275,068	[2],[3]		$ 272,264	275,068	[2],[3]	$ 272,264	$ 332,343
Impairment of Oil and Gas Properties		$ 94,000		$ 22,000		117,000
Non-cash impairment of our Oil and Gas equity investments						$ 5,170
[1]	The PPA under which Black Hills Colorado IPP provides generation to support Colorado Electric customers from the Pueblo Airport Generation Station is accounted for as a capital lease. As such, assets owned by our Power Generation segment are recorded at Colorado Electric under accounting for a capital lease.
[2]	As a result of continued low commodity prices during 2015, we recorded non-cash impairments of oil and gas assets included in our Oil and Gas segment of $94 million and $117 million for the for the three and six months ended June 30, 2015, respectively. See Note 16 to the Condensed Consolidated Financial statements in this Quarterly Report on Form 10-Q.
[3]	Includes a noncash impairment of our Oil and Gas equity investments of $5.2 million for the three and six months ended June 30, 2015.

Accounts Receivable_ Accounts40

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

Regulatory Accounting_ Regula41

Regulatory Accounting: Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory Assets		$ 227,972	$ 257,839	$ 202,961
Regulatory Liabilities		$ 161,745	148,831	120,290
Deferred energy and gas costs
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		1 year
Regulatory Liabilities	[1],[2]	$ 16,114	6,496	6,490
Employee benefit plans
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		12 years
Regulatory Liabilities	[3],[4]	$ 53,163	53,139	34,356
Cost of removal
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		44 years
Regulatory Liabilities	[2]	$ 84,118	78,249	70,841
Other regulatory liabilities
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		25 years
Regulatory Liabilities	[3]	$ 8,350	10,947	8,603
Deferred energy and gas costs
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		1 year
Regulatory Assets	[1],[2]	$ 26,862	23,820	29,605
Deferred gas cost adjustments
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		2 years
Regulatory Assets	[1],[2]	$ 5,588	37,471	35,479
Gas price derivatives
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		7 years
Regulatory Assets	[2]	$ 17,907	18,740	3,561
AFUDC
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		45 years
Regulatory Assets	[5]	$ 12,321	12,358	12,468
Employee benefit plans
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		12 years
Regulatory Assets	[3],[4]	$ 96,734	97,126	65,874
Environmental
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory Assets	[2]	$ 1,224	1,314	1,314
Asset retirement obligations
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		44 years
Regulatory Assets	[2]	$ 3,242	3,287	3,278
Bond issue cost
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		23 years
Regulatory Assets	[2]	$ 3,204	3,276	3,347
Renewable energy standard adjustment
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		5 years
Regulatory Assets	[2]	$ 5,629	9,622	14,501
Flow through accounting
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		35 years
Regulatory Assets	[3]	$ 27,861	25,887	22,754
Decommissioning costs
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		10 years
Regulatory Assets	[6]	$ 14,845	12,484	0
Other regulatory assets
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period		15 years
Regulatory Assets	[2]	$ 12,555	$ 12,454	$ 10,780
[1]	Our deferred energy, fuel cost, and gas cost adjustments represent the cost of electricity and gas delivered to our electric and gas utility customers that is either higher or lower than current rates and will be recovered or refunded in future rates. Fluctuations in deferred gas cost adjustments compared to the same period in the prior year are primarily due to higher natural gas prices driven by demand and market conditions from the peak winter heating season in the first part of 2014. Our electric and gas utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state utility commissions.
[2]	Recovery of costs, but we are not allowed a rate of return.
[3]	In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base, respectively.
[4]	Increase compared to June 30, 2014 was driven by a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.
[5]	In addition to recovery of costs, we are allowed a rate of return.
[6]	Black Hills Power has approximately $12 million of decommissioning costs associated with the retirements of the Neil Simpson I and Ben French power plants that are allowed a rate of return, in addition to recovery of costs.

Materials, Supplies and Fuel_42

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

Earnings Per Share_ Earnings 43

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

Earnings Per Share_ Anti-diluti

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

Notes Payable and Long-term D45

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

Notes Payable and Long-term D46

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

Risk Management Activities_ R47

Risk Management Activities: Risk Management Activities (Details) $ in Thousands		6 Months Ended		12 Months Ended
		Jun. 30, 2015USD ($)MMBTUbbl	Jun. 30, 2014USD ($)MMBTUbbl	Dec. 31, 2014USD ($)MMBTUbbl
Derivative [Line Items]
Derivative assets, current		$ 0	$ 1,737	$ 0
Derivative liabilities, current		3,289	3,480	3,340
Derivative liabilities, non-current		1,433	4,251	2,680
Oil and Gas [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months		6,400
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative liabilities, current		3,289	3,480	3,340
Derivative liabilities, non-current		1,433	4,251	2,680
Notional Amount	[1]	$ 75,000	$ 75,000	$ 75,000
Weighted average fixed interest rate		4.97%	4.97%	4.97%
Maximum Term		1 year 6 months	2 years 6 months	2 years
Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net		$ (3,300)
Crude Oil [Member] | Swaps and Options [Member] | Oil and Gas [Member]
Derivative [Line Items]
Notional amount - commodities | bbl	[2]	276,000	424,500	334,500
Maximum Term Hedged in Cash Flow Hedge	[3]	1 month	1 month	1 month
Derivative assets, current		$ 0	$ 0	$ 0
Derivative assets, non-current		0	0	0
Derivative liabilities, current		0	0	0
Derivative liabilities, non-current		$ 0	$ 0	$ 0
Natural Gas [Member] | Swap [Member] | Oil and Gas [Member]
Derivative [Line Items]
Notional amount - commodities | MMBTU	[2]	4,187,500	9,265,000	6,582,500
Maximum Term Hedged in Cash Flow Hedge	[3]	1 month	1 month	1 month
Derivative assets, current		$ 0	$ 0	$ 0
Derivative assets, non-current		0	0	0
Derivative liabilities, current		0	0	0
Derivative liabilities, non-current		0	0	0
Utilities Group [Member] | Natural Gas, Distribution [Member]
Derivative [Line Items]
Derivative assets, current		0	1,737	0
Derivative assets, non-current		0	0	0
Derivative liabilities, non-current		0	0	0
Net Unrealized (Gain) Loss Included in Regulatory assets or Regulatory liabilities		$ 17,907	$ 3,561	$ 18,740
Utilities Group [Member] | Natural Gas, Distribution [Member] | Future [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities | MMBTU		17,270,000	16,240,000	19,370,000
Maximum Term	[4]	66 months	78 months	72 months
Utilities Group [Member] | Natural Gas, Distribution [Member] | Commodity Option [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities | MMBTU		3,980,000	3,980,000	4,020,000
Maximum Term	[4]	9 months	9 months	8 months
Utilities Group [Member] | Natural Gas, Distribution [Member] | Basis Swap [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities | MMBTU		14,445,000	13,415,000	12,005,000
Maximum Term	[4]	54 months	66 months	60 months
[1]	These swaps are designated to borrowings on our Revolving Credit Facility, and are priced using three-month LIBOR, matching the floating portion of the related borrowings.
[2]	Crude oil in Bbls, natural gas in MMBtus.
[3]	Refers to the tenor of the derivative instrument. Assets and liabilities are classified as current/non-current based on the production month hedged and the corresponding settlement of the derivative instrument.
[4]	Term reflects the maximum forward period hedged.

Risk Management Activities_ Hed

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

Fair Value Measurements_ Fair49

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

Fair Value Measurements_ Balanc

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

Fair Value of Financial Instr51

Fair Value of Financial Instruments: Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents		$ 87,210	$ 21,218	$ 14,697	$ 7,841
Restricted cash and equivalents		2,316	2,056	2
Notes payable		105,760	75,000	132,700
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents		87,210	21,218	14,697
Restricted cash and equivalents		2,316	2,056	2
Notes payable		105,760	75,000	132,700
Long-term debt, including current maturities		1,567,727	1,542,589	1,396,950
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Fair Value	[1]	87,210	21,218	14,697
Restricted Cash Fair Value Disclosure	[1]	2,316	2,056	2
Notes payable, Fair Value	[1]	105,760	75,000	132,700
Long-term debt, including current maturities, Fair Value	[2]	$ 1,700,487	$ 1,734,555	$ 1,578,756
[1]	Carrying value approximates fair value due to either the short-term length of maturity or variable interest rates that approximate prevailing market rates, and therefore is classified in Level 1 in the fair value hierarchy.
[2]	Long-term debt is valued based on observable inputs available either directly or indirectly for similar liabilities in active markets and therefore is classified in Level 2 in the fair value hierarchy.

Other Comprehensive Income (L52

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

Other Comprehensive Income (L53

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

Supplemental Disclosure of Ca54

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

Employee Benefit Plans_ Emplo55

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

Commitments and Contingencies_

Commitments and Contingencies: Commitments and Contingencies - Oil Creek Fire (Details) - Pending Litigation [Member] - Oil Creek Fire [Member] - Loss from Catastrophes [Member] $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)
Minimum [Member]
Loss Contingencies [Line Items]
Insurance Coverage Deductible Per Occurrence	$ 1
Maximum [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 55

Commitments and Contingencies57

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

Impairment of Assets_ Impairmen

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

Impairment of Assets_ Equity in

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