Black Hills (BKH) 10-Q 5 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document Information [Line Items]
Entity Registrant Name	BLACK HILLS CORP /SD/
Entity Central Index Key	1130464
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		44,821,847
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (Loss) (unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$441,987	$460,169
Utilities -
Fuel, purchased power and cost of natural gas sold	205,327	230,468
Operations and maintenance	71,084	71,227
Non-regulated energy operations and maintenance	22,050	22,332
Depreciation, depletion and amortization	39,586	36,083
Taxes - property, production and severance	11,936	10,336
Other operating expenses	52	125
Total operating expenses	350,035	370,571
Operating income	91,952	89,598
Interest charges -
Interest expense incurred (including amortization of debt issuance costs, premiums and discounts and realized settlements on interest rate swaps)	-19,910	-17,860
Allowance for funds used during construction - borrowed	158	270
Capitalized interest	276	257
Interest income	448	390
Allowance for funds used during construction - equity	56	238
Other income (expense), net	331	592
Total other income (expense), net	-18,641	-16,113
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	73,311	73,485
Equity in earnings (loss) of unconsolidated subsidiaries	-297	-1
Income tax benefit (expense)	-25,120	-25,366
Net income (loss) available for common stock	$47,894	$48,118
Earnings (loss) per share of common stock:
Total income (loss) per share, Basic	$1.08	$1.09
Total income (loss) per share, Diluted	$1.07	$1.08
Weighted average common shares outstanding:
Basic	44,541	44,330
Diluted	44,660	44,554
Dividends declared per share of common stock	$0.41	$0.39

Condensed_Consolidated_Stateme1

Condensed Consolidated Statement of Comprehensive Income (unaudited) Statement (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss) available for common stock	$47,894	$48,118
Other comprehensive income (loss), net of tax:
Fair value adjustments on derivatives designated as cash flow hedges (net of tax (expense) benefit of $(1,042) and $1,307 for the three months ended 2015 and 2014, respectively)	1,836	-2,257
Reclassification adjustments for cash flow hedges settled and included in net income (loss) (net of tax (expense) benefit of $1,254 and $(425) for the three months ended 2015 and 2014, respectively)	-1,241	780
Benefit plan liability adjustments - net gain (loss) (net of tax (expense) benefit of $15 and $2 for the three months ended 2015 and 2014, respectively)	-27	-2
Benefit plan liability adjustments - prior service cost (net of tax (expense) benefit of $(90) for the three months ended 2014	0	164
Reclassification adjustments of benefit plan liability - prior service cost (net of tax (expense) benefit of $19 and $4 for the three months ended 2015 and 2014, respectively)	-36	-9
Reclassification adjustments of benefit plan liability - net gain (loss) (net of tax (expense) benefit of $(247) and $(85) for the three months ended 2015 and 2014, respectively)	458	157
Other comprehensive income (loss), net of tax	990	-1,167
Comprehensive income (loss) available for common stock	48,884	46,951
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures
Fair value adjustment on derivatives designated as cash flow hedges, (tax) benefit	-1,043	1,307
Reclassification adjustments of cash flow hedges settled and included in net income, (tax) benefit	1,254	-425
Benefit plan liability adjustments net gain, (tax) benefit	15	2
Benefit plan liability adjustments prior service cost, (tax) benefit	0	-90
Reclassification adjustment of benefit plan prior service cost included in net income, (tax) benefit	19	4
Reclassification adjustment of benefit plan liabilities actuarial gain (loss), (tax) benefit	($247)	($85)

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (unaudited) Statement (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$63,385	$21,218	$17,641
Restricted cash and equivalents	2,191	2,056	2
Accounts receivable, net	178,421	189,992	203,625
Materials, supplies and fuel	66,626	91,191	66,187
Derivative assets, current	0	0	1,846
Income tax receivable, net	159	2,053	1,826
Deferred income tax assets, net, current	23,913	48,288	25,780
Regulatory assets, current	56,542	74,396	62,946
Other current assets	47,448	24,842	24,563
Total current assets	438,685	454,036	404,416
Investments	17,210	17,294	16,916
Property, plant and equipment	4,652,058	4,563,400	4,318,194
Less: accumulated depreciation and depletion	-1,351,857	-1,324,025	-1,298,398
Total property, plant and equipment, net	3,300,201	3,239,375	3,019,796
Other assets:
Goodwill	353,396	353,396	353,396
Intangible assets, net	3,121	3,176	3,342
Regulatory assets, non-current	178,935	183,443	138,173
Other assets, non-current	28,280	29,086	28,925
Total other assets, non-current	563,732	569,101	523,836
TOTAL ASSETS	4,319,828	4,279,806	3,964,964
Current liabilities:
Accounts payable	88,770	124,139	149,681
Accrued liabilities	166,781	170,115	145,973
Derivative liabilities, current	3,342	3,340	3,498
Regulatory liabilities, current	17,621	3,687	583
Notes payable	102,600	75,000	100,000
Current maturities of long-term debt	0	275,000	0
Total current liabilities	379,114	651,281	399,735
Long-term debt, net of current maturities	1,542,658	1,267,589	1,396,949
Deferred credits and other liabilities:
Deferred income tax liabilities, net, non-current	522,290	523,716	466,856
Derivative liabilities, non-current	2,143	2,680	4,805
Regulatory liabilities, non-current	148,918	145,144	116,793
Benefit plan liabilities	162,334	158,966	113,324
Other deferred credits and other liabilities	154,604	154,406	129,083
Total deferred credits and other liabilities	990,289	984,912	830,861
Commitments and contingencies (See Notes 7, 8, 13, 14)
Stockholders’ equity:
Common stock $1 par value; 100,000,000 shares authorized; issued 44,856,790; 44,714,072; and 44,666,953 shares, respectively	44,857	44,714	44,667
Additional Paid in Capital	749,517	748,840	742,016
Retained earnings	629,135	599,389	570,963
Treasury stock, at cost – 33,755; 42,226; and 37,038 shares, respectively	-1,688	-1,875	-1,638
Accumulated other comprehensive income (loss)	-14,054	-15,044	-18,589
Total stockholders’ equity	1,407,767	1,376,024	1,337,419
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$4,319,828	$4,279,806	$3,964,964

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (unaudited) Condensed Consolidated Balance Sheets (Parentheticals) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Statement of Financial Position [Abstract]
Common Stock, Par Per Share	$1	$1	$1
Common Stock, Shares Issued	44,856,790	44,714,072	44,666,953
Treasury Stock, Shares	33,755	42,226	37,038
Common Stock, Shares Authorized	100,000,000	100,000,000	100,000,000

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net income (loss) available for common stock	$47,894	$48,118
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	39,586	36,083
Deferred financing cost amortization	519	568
Stock compensation	2,083	3,716
Deferred income taxes	22,048	25,953
Employee benefit plans	5,283	3,703
Other adjustments, net	6,748	5,190
Changes in certain operating assets and liabilities:
Materials, supplies and fuel	25,689	22,291
Accounts receivable, unbilled revenues and other operating assets	47,947	-78,576
Accounts payable and other operating liabilities	-44,652	29,074
Other operating activities, net	-1,658	1,978
Net Cash Provided by (Used in) Operating Activities	151,487	98,098
Investing activities:
Property, plant and equipment additions	-117,523	-83,609
Other investing activities	-348	-3,220
Net Cash Provided by (Used in) Investing Activities	-117,871	-86,829
Financing activities:
Dividends paid on common stock	-18,148	-17,399
Common stock issued	999	881
Short-term borrowings - issuances	77,700	86,800
Short-term borrowings - repayments	-50,100	-69,300
Other financing activities	-1,900	-2,451
Net Cash Provided by (Used in) Financing Activities	8,551	-1,469
Net change in cash and cash equivalents	42,167	9,800
Cash and Cash Equivalents
Cash and cash equivalents, beginning of period	21,218	7,841
Cash and cash equivalents, end of period	$63,385	$17,641

Managements_Statement

Management's Statement:	3 Months Ended
	Mar. 31, 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 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 March 31, 2015, December 31, 2014, and March 31, 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 months ended March 31, 2015 and March 31, 2014, and our financial condition as of March 31, 2015, December 31, 2014, and March 31, 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 April 1, 2015, FASB voted to propose to defer the effective date of ASU 2014-09 by one year. The proposed guidance would be effective for annual and interim reporting periods beginning after December 15, 2017 and early adoption is permitted. We are currently assessing the impact, if any, that ASU 2014-09 will have on our financial position, results of operations or cash flows.

Business_Segment_Information

Business Segment Information:	3 Months Ended
	Mar. 31, 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 March 31, 2015		External			Inter-company				Net Income (Loss)
			Operating			Operating
			Revenue			Revenue
	Utilities:
	Electric		$	182,974		$	3,424			$	18,929
	Gas		237,651			—				22,212
	Non-regulated Energy:
	Power Generation		1,953			20,721				8,145
	Coal Mining		8,142			7,792				3,010
	Oil and Gas		11,267			—				(5,071		)
	Corporate activities		—			—				669
	Inter-company eliminations		—			(31,937		)		—
	Total		$	441,987		$	—			$	47,894
	Three Months Ended March 31, 2014		External			Inter-company				Net Income (Loss)
			Operating			Operating
			Revenue			Revenue
	Utilities:
	Electric		$	178,095		$	4,007			$	14,575
	Gas		259,337			—				24,698
	Non-regulated Energy:
	Power Generation		1,269			21,079				8,073
	Coal Mining		6,618			8,880				2,464
	Oil and Gas		14,850			—				(2,022		)
	Corporate activities		—			—				330
	Inter-company eliminations		—			(33,966		)		—
	Total		$	460,169		$	—			$	48,118
	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:	31-Mar-15			31-Dec-14				31-Mar-14
	Utilities:
	Electric (a)	$	2,817,423		$	2,748,680			$	2,572,616
	Gas	839,802			906,922				842,660
	Non-regulated Energy:
	Power Generation (a)	75,945			76,945				90,643
	Coal Mining	77,399			74,407				74,523
	Oil and Gas	403,657			366,247				295,083
	Corporate activities	105,602			106,605				89,439
	Total assets	$	4,319,828		$	4,279,806			$	3,964,964
	__________
	(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.

Accounts_Receivable

Accounts Receivable:	3 Months Ended
	Mar. 31, 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
	31-Mar-15	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
	Electric Utilities	$	53,862	$	24,540	$	(834	)	$	77,568
	Gas Utilities	63,252		28,785		(1,588		)	90,449
	Power Generation	1,152		—		—			1,152
	Coal Mining	3,638		—		—			3,638
	Oil and Gas	4,646		—		(13		)	4,633
	Corporate	981		—		—			981
	Total	$	127,531	$	53,325	$	(2,435	)	$	178,421
		Accounts		Unbilled		Less Allowance for			Accounts
	31-Dec-14	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
	31-Mar-14	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
	Electric Utilities	$	53,733	$	20,063	$	(690	)	$	73,106
	Gas Utilities	77,982		35,791		(814		)	112,959
	Power Generation	1,340		—		—			1,340
	Coal Mining	2,616		—		—			2,616
	Oil and Gas	10,920		—		(13		)	10,907
	Corporate	2,697		—		—			2,697
	Total	$	149,288	$	55,854	$	(1,517	)	$	203,625

Regulatory_Accounting

Regulatory Accounting:	3 Months Ended
	Mar. 31, 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)	31-Mar-15		31-Dec-14		31-Mar-14
	Regulatory assets
	Deferred energy and fuel cost adjustments - current (a) (d)	1	$	30,833	$	23,820	$	23,935
	Deferred gas cost adjustments (a)(d)	2	6,138		37,471		38,505
	Gas price derivatives (a)	7	21,606		18,740		4,420
	AFUDC (b)	45	12,114		12,358		12,349
	Employee benefit plans (c) (e)	12	97,700		97,126		65,833
	Environmental (a)	subject to approval	1,240		1,314		1,317
	Asset retirement obligations (a)	44	3,237		3,287		3,271
	Bond issue cost (a)	23	3,240		3,276		3,383
	Renewable energy standard adjustment (a)	5	5,590		9,622		16,088
	Flow through accounting (c)	35	26,835		25,887		21,837
	Decommissioning costs	10	13,702		12,484		—
	Other regulatory assets (a)	15	13,242		12,454		10,181
			$	235,477	$	257,839	$	201,119
	Regulatory liabilities
	Deferred energy and gas costs (a) (d)	1	$	18,094	$	6,496	$	6,485
	Employee benefit plans (c) (e)	12	53,151		53,139		34,355
	Cost of removal (a)	44	81,449		78,249		67,640
	Other regulatory liabilities (c)	25	13,845		10,947		8,896
			$	166,539	$	148,831	$	117,376
	__________
	(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 March 31, 2014 is due to a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.

Materials_Supplies_and_Fuel

Materials, Supplies and Fuel:	3 Months Ended
	Mar. 31, 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:
		31-Mar-15		31-Dec-14		31-Mar-14
	Materials and supplies	$	52,429	$	49,555	$	50,727
	Fuel - Electric Utilities	6,780		6,637		7,218
	Natural gas in storage held for distribution	7,417		34,999		8,242
	Total materials, supplies and fuel	$	66,626	$	91,191	$	66,187

Earnings_Per_Share

Earnings Per Share:	3 Months Ended
	Mar. 31, 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) is as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Net income (loss) available for common stock	$	47,894		$	48,118
	Weighted average shares - basic	44,541			44,330
	Dilutive effect of:
	Equity compensation	119			224
	Weighted average shares - diluted	44,660			44,554
	The following outstanding securities were not included in the computation of diluted earnings per share as their effect would have been anti-dilutive (in thousands):
		Three Months Ended March 31,
		2015		2014
	Equity compensation	107		46
	Anti-dilutive shares	107		46

Notes_Payable_and_Longterm_Deb

Notes Payable and Long-term Debt:

3 Months Ended

Mar. 31, 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:

31-Mar-15

31-Dec-14

31-Mar-14

Balance Outstanding

Letters of Credit

Balance Outstanding

Letters of Credit

Balance Outstanding

Letters of Credit

Revolving Credit Facility

$

102,600

$

22,300

$

75,000

$

35,000

$

100,000

$

27,700

Revolving Credit Facility

On May 29, 2014, we amended our $500 million corporate Revolving Credit Facility agreement to extend the term through May 29, 2019. This facility is substantially 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 March 31, 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. In accordance with the terms of the agreement, the $275 million Corporate term loan is classified as Long-Term Debt as of March 31, 2015. The additional $25 million, less interest and fees, will be 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 March 31, 2015

Covenant Requirement

Recourse Leverage Ratio

55%

Less than

65%

As of March 31, 2015, we were in compliance with this covenant.

Risk_Management_Activities

Risk Management Activities:	3 Months Ended
	Mar. 31, 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.
	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 9.
	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:
		31-Mar-15							31-Dec-14						31-Mar-14
		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)	305,000			5,367,500				334,500			6,582,500			442,500		8,296,250
	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 March 31, 2015, prices a $9.9 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:
		31-Mar-15					31-Dec-14					31-Mar-14
		Notional			Maximum		Notional			Maximum		Notional		Maximum
		(MMBtus)			Term		(MMBtus)			Term		(MMBtus)		Term
					(months) (a)					(months) (a)				(months) (a)
	Natural gas futures purchased	17,280,000			69		19,370,000			72		16,140,000		80
	Natural gas options purchased	1,320,000			12		4,020,000			8		1,320,000		12
	Natural gas basis swaps purchased	15,735,000			57		12,005,000			60		14,575,000		69
	__________
	(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):
		31-Mar-15			31-Dec-14			31-Mar-14
	Derivative assets, current	$	—		$	—		$	1,846
	Derivative assets, non-current	$	—		$	—		$	—
	Derivative liabilities, non-current	$	—		$	—		$	—
	Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities	$	21,606		$	18,740		$	4,420
	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:
		31-Mar-15				31-Dec-14				31-Mar-14
		Interest Rate				Interest Rate				Interest Rate
		Swaps (a)				Swaps (a)				Swaps (a)
	Notional	$	75,000			$	75,000			$	75,000
	Weighted average fixed interest rate	4.97		%		4.97		%		4.97		%
	Maximum terms in years	1.75				2				2.75
	Derivative liabilities, current	$	3,342			$	3,340			$	3,498
	Derivative liabilities, non-current	$	2,143			$	2,680			$	4,805
	__________
	(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 March 31, 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 March 31, 2015
	Derivatives in Cash Flow Hedging Relationships		Amount of				Location		Amount of				Location of	Amount of
			Gain/(Loss)				of Gain/(Loss)		Reclassified				Gain/(Loss)	Gain/(Loss)
Recognized			Reclassified	Gain/(Loss)			Recognized		Recognized in
in AOCI			from AOCI	from AOCI			in Income		Income on
Derivative			into Income	into Income			on Derivative		Derivative
(Effective			(Effective	(Effective			(Ineffective		(Ineffective
Portion)			Portion)	Portion)			Portion)		Portion)
Interest rate swaps		$	(886	)		Interest expense		$	1,437				$	—
Commodity derivatives		3,764				Revenue		(3,932		)			—
Total		$	2,878					$	(2,495	)			$	—
Three Months Ended March 31, 2014
Derivatives in Cash Flow Hedging Relationships		Amount of				Location		Amount of				Location of	Amount of
		Gain/(Loss)				of Gain/(Loss)		Reclassified				Gain/(Loss)	Gain/(Loss)
		Recognized				Reclassified		Gain/(Loss)				Recognized	Recognized in
		in AOCI				from AOCI		from AOCI				in Income	Income on
		Derivative				into Income		into Income				on Derivative	Derivative
		(Effective				(Effective		(Effective				(Ineffective	(Ineffective
		Portion)				Portion)		Portion)				Portion)	Portion)
Interest rate swaps		$	(91	)		Interest expense		$	(894	)			$	—
Commodity derivatives		(3,473		)		Revenue		(311		)			—
Total		$	(3,564	)				$	(1,205	)			$	—

Fair_Value_Measurements

Fair Value Measurements:	3 Months Ended
	Mar. 31, 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 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 Chicago Mercantile Exchange pricing for similar instruments.
	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 10:
		As of March 31, 2015
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(in thousands)
	Assets:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			8,096			—		(8,096		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			6,526			—		(6,526		)	—
	Commodity derivatives — Utilities	—			1,184			—		(1,184		)	—
	Total	$	—		$	15,806		$	—	$	(15,806	)	$	—
	Liabilities:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			2			—		(2		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			256			—		(256		)	—
	Commodity derivatives — Utilities	—			22,002			—		(22,002		)	—
	Interest rate swaps	—			5,485			—		—			5,485
	Total	$	—		$	27,745		$	—	$	(22,260	)	$	5,485
		As of December 31, 2014
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(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 March 31, 2014
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(in thousands)
	Assets:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			7			—		(7		)	—
Options -- Gas	—			—			—		—			—
Basis Swaps -- Gas	—			490			—		(490		)	—
Commodity derivatives — Utilities	—			3,226			—		(1,380		)	1,846
Total	$	—		$	3,723		$	—	$	(1,877	)	$	1,846
Liabilities:
Commodity derivatives — Oil and Gas
Options -- Oil	$	—		$	—		$	—	$	—		$	—
Basis Swaps -- Oil	—			1,983			—		(1,983		)	—
Options -- Gas	—			—			—		—			—
Basis Swaps -- Gas	—			2,114			—		(2,114		)	—
Commodity derivatives — Utilities	—			6,919			—		(6,919		)	—
Interest rate swaps	—			8,303			—		—			8,303
Total	$	—		$	19,319		$	—	$	(11,016	)	$	8,303
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 reflecting 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 March 31, 2015, December 31, 2014, and March 31, 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 8.
The following tables present the fair value and balance sheet classification of our derivative instruments (in thousands):
As of March 31, 2015
	Balance Sheet Location		Fair Value			Fair Value
			of Asset			of Liability
			Derivatives			Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current		$	9,989		$	—
Commodity derivatives	Derivative assets — non-current		4,633			—
Commodity derivatives	Derivative liabilities — current		—			126
Commodity derivatives	Derivative liabilities — non-current		—			132
Interest rate swaps	Derivative liabilities — current		—			3,342
Interest rate swaps	Derivative liabilities — non-current		—			2,143
Total derivatives designated as hedges			$	14,622		$	5,743
Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current		$	—		$	—
Commodity derivatives	Derivative assets — non-current		—			—
Commodity derivatives	Derivative liabilities — current		—			7,530
Commodity derivatives	Derivative liabilities — non-current		—			13,288
Total derivatives not designated as hedges			$	—		$	20,818
As of December 31, 2014
	Balance Sheet Location		Fair Value			Fair Value
			of Asset			of Liability
			Derivatives			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 March 31, 2014
	Balance Sheet Location		Fair Value			Fair Value
			of Asset			of Liability
			Derivatives			Derivatives
Derivatives designated as hedges:
Commodity derivatives	Derivative assets — current		$	30		$	—
Commodity derivatives	Derivative assets — non-current		466			—
Commodity derivatives	Derivative liabilities — current		—			3,187
Commodity derivatives	Derivative liabilities — non-current		—			910
Interest rate swaps	Derivative liabilities — current		—			3,498
Interest rate swaps	Derivative liabilities — non-current		—			4,805
Total derivatives designated as hedges			$	496		$	12,400
Derivatives not designated as hedges:
Commodity derivatives	Derivative assets — current		$	1,846		$	—
Commodity derivatives	Derivative assets — non-current		—			—
Commodity derivatives	Derivative liabilities — current		—			—
Commodity derivatives	Derivative liabilities — non-current		—			5,539
Interest rate swaps	Derivative liabilities — current		—			—
Interest rate swaps	Derivative liabilities — non-current		—			—
Total derivatives not designated as hedges			$	1,846		$	5,539

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments:	3 Months Ended
	Mar. 31, 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 9, were as follows (in thousands) as of:
		31-Mar-15				31-Dec-14				31-Mar-14
		Carrying		Fair Value		Carrying		Fair Value		Carrying		Fair Value
		Amount				Amount				Amount
	Cash and cash equivalents (a)	$	63,385	$	63,385	$	21,218	$	21,218	$	17,641	$	17,641
	Restricted cash and equivalents (a)	$	2,191	$	2,191	$	2,056	$	2,056	$	2	$	2
	Notes payable (a)	$	102,600	$	102,600	$	75,000	$	75,000	$	100,000	$	100,000
	Long-term debt, including current maturities (b)	$	1,542,658	$	1,767,113	$	1,542,589	$	1,734,555	$	1,396,949	$	1,541,727
	__________
	(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):	3 Months Ended
	Mar. 31, 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
			31-Mar-15			31-Mar-14
	Gains (losses) on cash flow hedges:
	Interest rate swaps	Interest expense	$	1,437		$	894
	Commodity contracts	Revenue	(3,932		)	311
			(2,495		)	1,205
	Income tax	Income tax benefit (expense)	1,254			(425		)
	Reclassification adjustments related to cash flow hedges, net of tax		$	(1,241	)	$	780
	Amortization of defined benefit plans:
	Prior service cost	Utilities - Operations and maintenance	$	(27	)	$	(25	)
		Non-regulated energy operations and maintenance	(28		)	12
	Actuarial gain (loss)	Utilities - Operations and maintenance	454			157
		Non-regulated energy operations and maintenance	251			85
			650			229
	Income tax	Income tax benefit (expense)	(228		)	(81		)
	Reclassification adjustments related to defined benefit plans, net of tax		$	422		$	148
	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	)
	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	)

Supplemental_Disclosure_of_Cas

Supplemental Disclosure of Cash Flow Information:	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information	SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
	Three months ended	31-Mar-15			31-Mar-14
		(in thousands)
	Non-cash investing and financing activities from continuing operations—
	Property, plant and equipment acquired with accrued liabilities	$	33,534		$	40,939
	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)	$	(10,909	)	$	(11,452	)
	Income taxes, net	$	(2	)	$	4

Employee_Benefit_Plans

Employee Benefit Plans:	3 Months Ended
	Mar. 31, 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 March 31,
		2015			2014
	Service cost	$	1,494		$	1,362
	Interest cost	3,880			3,963
	Expected return on plan assets	(4,867		)	(4,516		)
	Prior service cost	15			16
	Net loss (gain)	2,759			1,201
	Net periodic benefit cost	$	3,281		$	2,026
	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 March 31,
		2015			2014
	Service cost	$	464		$	425
	Interest cost	450			479
	Expected return on plan assets	(33		)	(21		)
	Prior service cost (benefit)	(107		)	(107		)
	Net loss (gain)	102			40
	Net periodic benefit cost	$	876		$	816
	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 March 31,
		2015			2014
	Service cost	$	491		$	374
	Interest cost	364			362
	Prior service cost	1			1
	Net loss (gain)	270			124
	Net periodic benefit cost	$	1,126		$	861
	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			Additional Contributions			Contributions
		Three Months Ended March 31, 2015			Anticipated for 2015			Anticipated for 2016
	Defined Benefit Pension Plans	$	—		$	10,200		$	10,200
	Non-pension Defined Benefit Postretirement Healthcare Plans	$	939		$	2,816		$	4,026
	Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	372		$	1,115		$	1,544

Commitments_and_Contingencies

Commitments and Contingencies:	3 Months Ended
	Mar. 31, 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 except for those described below.
	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 March 31, 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 March 31, 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 March 31, 2015, the restricted net assets at our Utilities Group were approximately $338 million.

Business_Segment_Information_B

Business Segment Information: Business Segment Information (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2015		External			Inter-company				Net Income (Loss)
			Operating			Operating
			Revenue			Revenue
	Utilities:
	Electric		$	182,974		$	3,424			$	18,929
	Gas		237,651			—				22,212
	Non-regulated Energy:
	Power Generation		1,953			20,721				8,145
	Coal Mining		8,142			7,792				3,010
	Oil and Gas		11,267			—				(5,071		)
	Corporate activities		—			—				669
	Inter-company eliminations		—			(31,937		)		—
	Total		$	441,987		$	—			$	47,894
	Three Months Ended March 31, 2014		External			Inter-company				Net Income (Loss)
			Operating			Operating
			Revenue			Revenue
	Utilities:
	Electric		$	178,095		$	4,007			$	14,575
	Gas		259,337			—				24,698
	Non-regulated Energy:
	Power Generation		1,269			21,079				8,073
	Coal Mining		6,618			8,880				2,464
	Oil and Gas		14,850			—				(2,022		)
	Corporate activities		—			—				330
	Inter-company eliminations		—			(33,966		)		—
	Total		$	460,169		$	—			$	48,118
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:	31-Mar-15			31-Dec-14				31-Mar-14
	Utilities:
	Electric (a)	$	2,817,423		$	2,748,680			$	2,572,616
	Gas	839,802			906,922				842,660
	Non-regulated Energy:
	Power Generation (a)	75,945			76,945				90,643
	Coal Mining	77,399			74,407				74,523
	Oil and Gas	403,657			366,247				295,083
	Corporate activities	105,602			106,605				89,439
	Total assets	$	4,319,828		$	4,279,806			$	3,964,964
	__________
	(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.

Accounts_Receivable_Accounts_R

Accounts Receivable: Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 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
	31-Mar-15	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
	Electric Utilities	$	53,862	$	24,540	$	(834	)	$	77,568
	Gas Utilities	63,252		28,785		(1,588		)	90,449
	Power Generation	1,152		—		—			1,152
	Coal Mining	3,638		—		—			3,638
	Oil and Gas	4,646		—		(13		)	4,633
	Corporate	981		—		—			981
	Total	$	127,531	$	53,325	$	(2,435	)	$	178,421
		Accounts		Unbilled		Less Allowance for			Accounts
	31-Dec-14	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
	31-Mar-14	Receivable, Trade		Revenue		Doubtful Accounts			Receivable, net
	Electric Utilities	$	53,733	$	20,063	$	(690	)	$	73,106
	Gas Utilities	77,982		35,791		(814		)	112,959
	Power Generation	1,340		—		—			1,340
	Coal Mining	2,616		—		—			2,616
	Oil and Gas	10,920		—		(13		)	10,907
	Corporate	2,697		—		—			2,697
	Total	$	149,288	$	55,854	$	(1,517	)	$	203,625

Regulatory_Accounting_Regulato

Regulatory Accounting: Regulatory Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 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)	31-Mar-15		31-Dec-14		31-Mar-14
	Regulatory assets
	Deferred energy and fuel cost adjustments - current (a) (d)	1	$	30,833	$	23,820	$	23,935
	Deferred gas cost adjustments (a)(d)	2	6,138		37,471		38,505
	Gas price derivatives (a)	7	21,606		18,740		4,420
	AFUDC (b)	45	12,114		12,358		12,349
	Employee benefit plans (c) (e)	12	97,700		97,126		65,833
	Environmental (a)	subject to approval	1,240		1,314		1,317
	Asset retirement obligations (a)	44	3,237		3,287		3,271
	Bond issue cost (a)	23	3,240		3,276		3,383
	Renewable energy standard adjustment (a)	5	5,590		9,622		16,088
	Flow through accounting (c)	35	26,835		25,887		21,837
	Decommissioning costs	10	13,702		12,484		—
	Other regulatory assets (a)	15	13,242		12,454		10,181
			$	235,477	$	257,839	$	201,119
	Regulatory liabilities
	Deferred energy and gas costs (a) (d)	1	$	18,094	$	6,496	$	6,485
	Employee benefit plans (c) (e)	12	53,151		53,139		34,355
	Cost of removal (a)	44	81,449		78,249		67,640
	Other regulatory liabilities (c)	25	13,845		10,947		8,896
			$	166,539	$	148,831	$	117,376
	__________
	(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 March 31, 2014 is due to a decrease in the discount rate and a change in the mortality tables used in employee benefit plan estimates.

Materials_Supplies_and_Fuel_Ma

Materials, Supplies and Fuel: Materials, Supplies and Fuel (Tables)	3 Months Ended
	Mar. 31, 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:
		31-Mar-15		31-Dec-14		31-Mar-14
	Materials and supplies	$	52,429	$	49,555	$	50,727
	Fuel - Electric Utilities	6,780		6,637		7,218
	Natural gas in storage held for distribution	7,417		34,999		8,242
	Total materials, supplies and fuel	$	66,626	$	91,191	$	66,187

Earnings_Per_Share_Earnings_Pe

Earnings Per Share: Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 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) is as follows (in thousands):
		Three Months Ended March 31,
		2015			2014
	Net income (loss) available for common stock	$	47,894		$	48,118
	Weighted average shares - basic	44,541			44,330
	Dilutive effect of:
	Equity compensation	119			224
	Weighted average shares - diluted	44,660			44,554
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding securities were not included in the computation of diluted earnings per share as their effect would have been anti-dilutive (in thousands):
		Three Months Ended March 31,
		2015		2014
	Equity compensation	107		46
	Anti-dilutive shares	107		46

Notes_Payable_and_Longterm_Deb1

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

3 Months Ended

Mar. 31, 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:

31-Mar-15

31-Dec-14

31-Mar-14

Balance Outstanding

Letters of Credit

Balance Outstanding

Letters of Credit

Balance Outstanding

Letters of Credit

Revolving Credit Facility

$

102,600

$

22,300

$

75,000

$

35,000

$

100,000

$

27,700

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 March 31, 2015

Covenant Requirement

Recourse Leverage Ratio

55%

Less than

65%

Risk_Management_Activities_Ris

Risk Management Activities: Risk Management Activities (Tables)	3 Months Ended
	Mar. 31, 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:
		31-Mar-15				31-Dec-14				31-Mar-14
		Interest Rate				Interest Rate				Interest Rate
		Swaps (a)				Swaps (a)				Swaps (a)
	Notional	$	75,000			$	75,000			$	75,000
	Weighted average fixed interest rate	4.97		%		4.97		%		4.97		%
	Maximum terms in years	1.75				2				2.75
	Derivative liabilities, current	$	3,342			$	3,340			$	3,498
	Derivative liabilities, non-current	$	2,143			$	2,680			$	4,805
	__________
	(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 March 31, 2015
	Derivatives in Cash Flow Hedging Relationships		Amount of				Location		Amount of				Location of	Amount of
			Gain/(Loss)				of Gain/(Loss)		Reclassified				Gain/(Loss)	Gain/(Loss)
			Recognized				Reclassified		Gain/(Loss)				Recognized	Recognized in
			in AOCI				from AOCI		from AOCI				in Income	Income on
			Derivative				into Income		into Income				on Derivative	Derivative
			(Effective				(Effective		(Effective				(Ineffective	(Ineffective
			Portion)				Portion)		Portion)				Portion)	Portion)
	Interest rate swaps		$	(886	)		Interest expense		$	1,437				$	—
	Commodity derivatives		3,764				Revenue		(3,932		)			—
	Total		$	2,878					$	(2,495	)			$	—
	Three Months Ended March 31, 2014
	Derivatives in Cash Flow Hedging Relationships		Amount of				Location		Amount of				Location of	Amount of
			Gain/(Loss)				of Gain/(Loss)		Reclassified				Gain/(Loss)	Gain/(Loss)
			Recognized				Reclassified		Gain/(Loss)				Recognized	Recognized in
			in AOCI				from AOCI		from AOCI				in Income	Income on
			Derivative				into Income		into Income				on Derivative	Derivative
			(Effective				(Effective		(Effective				(Ineffective	(Ineffective
			Portion)				Portion)		Portion)				Portion)	Portion)
	Interest rate swaps		$	(91	)		Interest expense		$	(894	)			$	—
	Commodity derivatives		(3,473		)		Revenue		(311		)			—
	Total		$	(3,564	)				$	(1,205	)			$	—
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:
		31-Mar-15							31-Dec-14						31-Mar-14
		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)	305,000			5,367,500				334,500			6,582,500			442,500		8,296,250
	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):
		31-Mar-15			31-Dec-14			31-Mar-14
	Derivative assets, current	$	—		$	—		$	1,846
	Derivative assets, non-current	$	—		$	—		$	—
	Derivative liabilities, non-current	$	—		$	—		$	—
	Net unrealized (gain) loss included in Regulatory assets or Regulatory liabilities	$	21,606		$	18,740		$	4,420
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:
		31-Mar-15					31-Dec-14					31-Mar-14
		Notional			Maximum		Notional			Maximum		Notional		Maximum
		(MMBtus)			Term		(MMBtus)			Term		(MMBtus)		Term
					(months) (a)					(months) (a)				(months) (a)
	Natural gas futures purchased	17,280,000			69		19,370,000			72		16,140,000		80
	Natural gas options purchased	1,320,000			12		4,020,000			8		1,320,000		12
	Natural gas basis swaps purchased	15,735,000			57		12,005,000			60		14,575,000		69
	__________
	(a) Term reflects the maximum forward period hedged.

Fair_Value_Measurements_Fair_V

Fair Value Measurements: Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 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 10:
		As of March 31, 2015
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(in thousands)
	Assets:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			8,096			—		(8,096		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			6,526			—		(6,526		)	—
	Commodity derivatives — Utilities	—			1,184			—		(1,184		)	—
	Total	$	—		$	15,806		$	—	$	(15,806	)	$	—
	Liabilities:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			2			—		(2		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			256			—		(256		)	—
	Commodity derivatives — Utilities	—			22,002			—		(22,002		)	—
	Interest rate swaps	—			5,485			—		—			5,485
	Total	$	—		$	27,745		$	—	$	(22,260	)	$	5,485
		As of December 31, 2014
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(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 March 31, 2014
		Level 1			Level 2			Level 3		Cash Collateral and Counterparty			Total
										Netting
		(in thousands)
	Assets:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			7			—		(7		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			490			—		(490		)	—
	Commodity derivatives — Utilities	—			3,226			—		(1,380		)	1,846
	Total	$	—		$	3,723		$	—	$	(1,877	)	$	1,846
	Liabilities:
	Commodity derivatives — Oil and Gas
	Options -- Oil	$	—		$	—		$	—	$	—		$	—
	Basis Swaps -- Oil	—			1,983			—		(1,983		)	—
	Options -- Gas	—			—			—		—			—
	Basis Swaps -- Gas	—			2,114			—		(2,114		)	—
	Commodity derivatives — Utilities	—			6,919			—		(6,919		)	—
	Interest rate swaps	—			8,303			—		—			8,303
	Total	$	—		$	19,319		$	—	$	(11,016	)	$	8,303
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 March 31, 2015
		Balance Sheet Location		Fair Value			Fair Value
				of Asset			of Liability
				Derivatives			Derivatives
	Derivatives designated as hedges:
	Commodity derivatives	Derivative assets — current		$	9,989		$	—
	Commodity derivatives	Derivative assets — non-current		4,633			—
	Commodity derivatives	Derivative liabilities — current		—			126
	Commodity derivatives	Derivative liabilities — non-current		—			132
	Interest rate swaps	Derivative liabilities — current		—			3,342
	Interest rate swaps	Derivative liabilities — non-current		—			2,143
	Total derivatives designated as hedges			$	14,622		$	5,743
	Derivatives not designated as hedges:
	Commodity derivatives	Derivative assets — current		$	—		$	—
	Commodity derivatives	Derivative assets — non-current		—			—
	Commodity derivatives	Derivative liabilities — current		—			7,530
	Commodity derivatives	Derivative liabilities — non-current		—			13,288
	Total derivatives not designated as hedges			$	—		$	20,818
	As of December 31, 2014
		Balance Sheet Location		Fair Value			Fair Value
				of Asset			of Liability
				Derivatives			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 March 31, 2014
		Balance Sheet Location		Fair Value			Fair Value
				of Asset			of Liability
				Derivatives			Derivatives
	Derivatives designated as hedges:
	Commodity derivatives	Derivative assets — current		$	30		$	—
	Commodity derivatives	Derivative assets — non-current		466			—
	Commodity derivatives	Derivative liabilities — current		—			3,187
	Commodity derivatives	Derivative liabilities — non-current		—			910
	Interest rate swaps	Derivative liabilities — current		—			3,498
	Interest rate swaps	Derivative liabilities — non-current		—			4,805
	Total derivatives designated as hedges			$	496		$	12,400
	Derivatives not designated as hedges:
	Commodity derivatives	Derivative assets — current		$	1,846		$	—
	Commodity derivatives	Derivative assets — non-current		—			—
	Commodity derivatives	Derivative liabilities — current		—			—
	Commodity derivatives	Derivative liabilities — non-current		—			5,539
	Interest rate swaps	Derivative liabilities — current		—			—
	Interest rate swaps	Derivative liabilities — non-current		—			—
	Total derivatives not designated as hedges			$	1,846		$	5,539

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments: Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 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 9, were as follows (in thousands) as of:
		31-Mar-15				31-Dec-14				31-Mar-14
		Carrying		Fair Value		Carrying		Fair Value		Carrying		Fair Value
		Amount				Amount				Amount
	Cash and cash equivalents (a)	$	63,385	$	63,385	$	21,218	$	21,218	$	17,641	$	17,641
	Restricted cash and equivalents (a)	$	2,191	$	2,191	$	2,056	$	2,056	$	2	$	2
	Notes payable (a)	$	102,600	$	102,600	$	75,000	$	75,000	$	100,000	$	100,000
	Long-term debt, including current maturities (b)	$	1,542,658	$	1,767,113	$	1,542,589	$	1,734,555	$	1,396,949	$	1,541,727
	__________
	(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_Los1

Other Comprehensive Income (Loss): Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 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
			31-Mar-15			31-Mar-14
	Gains (losses) on cash flow hedges:
	Interest rate swaps	Interest expense	$	1,437		$	894
	Commodity contracts	Revenue	(3,932		)	311
			(2,495		)	1,205
	Income tax	Income tax benefit (expense)	1,254			(425		)
	Reclassification adjustments related to cash flow hedges, net of tax		$	(1,241	)	$	780
	Amortization of defined benefit plans:
	Prior service cost	Utilities - Operations and maintenance	$	(27	)	$	(25	)
		Non-regulated energy operations and maintenance	(28		)	12
	Actuarial gain (loss)	Utilities - Operations and maintenance	454			157
		Non-regulated energy operations and maintenance	251			85
			650			229
	Income tax	Income tax benefit (expense)	(228		)	(81		)
	Reclassification adjustments related to defined benefit plans, net of tax		$	422		$	148
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	)
	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	)

Supplemental_Disclosure_of_Cas1

Supplemental Disclosure of Cash Flow Information: Supplemental Disclosure of Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information
	Three months ended	31-Mar-15			31-Mar-14
		(in thousands)
	Non-cash investing and financing activities from continuing operations—
	Property, plant and equipment acquired with accrued liabilities	$	33,534		$	40,939
	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)	$	(10,909	)	$	(11,452	)
	Income taxes, net	$	(2	)	$	4

Employee_Benefit_Plans_Employe

Employee Benefit Plans: Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 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 March 31,
		2015			2014
	Service cost	$	1,494		$	1,362
	Interest cost	3,880			3,963
	Expected return on plan assets	(4,867		)	(4,516		)
	Prior service cost	15			16
	Net loss (gain)	2,759			1,201
	Net periodic benefit cost	$	3,281		$	2,026
	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 March 31,
		2015			2014
	Service cost	$	464		$	425
	Interest cost	450			479
	Expected return on plan assets	(33		)	(21		)
	Prior service cost (benefit)	(107		)	(107		)
	Net loss (gain)	102			40
	Net periodic benefit cost	$	876		$	816
	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 March 31,
		2015			2014
	Service cost	$	491		$	374
	Interest cost	364			362
	Prior service cost	1			1
	Net loss (gain)	270			124
	Net periodic benefit cost	$	1,126		$	861
Schedule of Defined Benefit Plans Contributions	Contributions and anticipated contributions are as follows (in thousands):
		Contributions Made			Additional Contributions			Contributions
		Three Months Ended March 31, 2015			Anticipated for 2015			Anticipated for 2016
	Defined Benefit Pension Plans	$	—		$	10,200		$	10,200
	Non-pension Defined Benefit Postretirement Healthcare Plans	$	939		$	2,816		$	4,026
	Supplemental Non-qualified Defined Benefit and Defined Contribution Plans	$	372		$	1,115		$	1,544

Business_Segment_Information_I

Business Segment Information: Information Relating to Segment Statement of Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information
Revenue	$441,987	$460,169
Net Income (Loss)	47,894	48,118
Inter-company eliminations [Member]
Segment Reporting Information
Revenue	-31,937	-33,966
Net Income (Loss)	0	0
Corporate activities[Member]
Segment Reporting Information
Revenue	0	0
Net Income (Loss)	669	330
Consolidation, Eliminations [Member]
Segment Reporting Information
Revenue	0	0
Electric Utilities [Member]
Segment Reporting Information
Revenue	182,974	178,095
Net Income (Loss)	18,929	14,575
Electric Utilities [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	3,424	4,007
Gas Utilities [Member]
Segment Reporting Information
Revenue	237,651	259,337
Net Income (Loss)	22,212	24,698
Gas Utilities [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	0	0
Power Generation [Member]
Segment Reporting Information
Revenue	1,953	1,269
Net Income (Loss)	8,145	8,073
Power Generation [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	20,721	21,079
Coal Mining [Member]
Segment Reporting Information
Revenue	8,142	6,618
Net Income (Loss)	3,010	2,464
Coal Mining [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	7,792	8,880
Oil and Gas [Member]
Segment Reporting Information
Revenue	11,267	14,850
Net Income (Loss)	-5,071	-2,022
Oil and Gas [Member] | Inter-company eliminations [Member]
Segment Reporting Information
Revenue	$0	$0

Business_Segment_Information_S

Business Segment Information: Segment and Corporate Assets (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
In Thousands, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$4,319,828		$4,279,806		$3,964,964
Corporate activities[Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	105,602		106,605		89,439
Electric Utilities [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,817,423	[1]	2,748,680	[1]	2,572,616	[1]
Gas Utilities [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	839,802		906,922		842,660
Power Generation [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	75,945	[1]	76,945	[1]	90,643	[1]
Coal Mining [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	77,399		74,407		74,523
Oil and Gas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$403,657		$366,247		$295,083
[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.

Accounts_Receivable_Accounts_R1

Accounts Receivable: Accounts Receivable (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	($2,435)	($1,516)	($1,517)
Accounts receivable, net	178,421	189,992	203,625
Corporate[Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	981	2,555	2,697
Electric Utilities [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	-834	-722	-690
Accounts receivable, net	77,568	85,466	73,106
Gas Utilities [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	-1,588	-781	-814
Accounts receivable, net	90,449	92,159	112,959
Power Generation [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	1,152	1,369	1,340
Coal Mining [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	0	0	0
Accounts receivable, net	3,638	3,151	2,616
Oil and Gas [Member]
Accounts Receivable [Line Items]
Allowance for Doubtful Accounts	-13	-13	-13
Accounts receivable, net	4,633	5,292	10,907
Billed Revenues [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	127,531	119,488	149,288
Billed Revenues [Member] | Corporate[Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	981	2,555	2,697
Billed Revenues [Member] | Electric Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	53,862	59,714	53,733
Billed Revenues [Member] | Gas Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	63,252	47,394	77,982
Billed Revenues [Member] | Power Generation [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	1,152	1,369	1,340
Billed Revenues [Member] | Coal Mining [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	3,638	3,151	2,616
Billed Revenues [Member] | Oil and Gas [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	4,646	5,305	10,920
Unbilled Revenues [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	53,325	72,020	55,854
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	24,540	26,474	20,063
Unbilled Revenues [Member] | Gas Utilities [Member]
Accounts Receivable [Line Items]
Accounts Receivable, Trade	28,785	45,546	35,791
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_Regulato1

Regulatory Accounting: Regulatory Assets and Liabilities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory Assets	$235,477		$257,839		$201,119
Regulatory Liabilities	166,539		148,831		117,376
Deferred energy and gas costs
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	1 year
Regulatory Liabilities	18,094	[1],[2]	6,496	[1],[2]	6,485	[1],[2]
Employee benefit plans
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	12 years
Regulatory Liabilities	53,151	[3],[4]	53,139	[3],[4]	34,355	[3],[4]
Cost of removal
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	44 years
Regulatory Liabilities	81,449	[1]	78,249	[1]	67,640	[1]
Other regulatory liabilities
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	25 years
Regulatory Liabilities	13,845	[3]	10,947	[3]	8,896	[3]
Deferred energy and fuel cost adjustments - current
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	1 year
Regulatory Assets	30,833	[1],[2]	23,820	[1],[2]	23,935	[1],[2]
Deferred gas cost adjustments
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	2 years
Regulatory Assets	6,138	[1],[2]	37,471	[1],[2]	38,505	[1],[2]
Gas price derivatives
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	7 years
Regulatory Assets	21,606	[1]	18,740	[1]	4,420	[1]
AFUDC
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	45 years
Regulatory Assets	12,114	[5]	12,358	[5]	12,349	[5]
Employee benefit plans
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	12 years
Regulatory Assets	97,700	[3],[4]	97,126	[3],[4]	65,833	[3],[4]
Environmental
Schedule Of Regulatory Assets And Liabilities [Line Items]
Regulatory Assets	1,240	[1]	1,314	[1]	1,317	[1]
Asset retirement obligations
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	44 years
Regulatory Assets	3,237	[1]	3,287	[1]	3,271	[1]
Bond issue cost
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	23 years
Regulatory Assets	3,240	[1]	3,276	[1]	3,383	[1]
Renewable energy standard adjustment
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	5 years
Regulatory Assets	5,590	[1]	9,622	[1]	16,088	[1]
Flow through accounting
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	35 years
Regulatory Assets	26,835	[3]	25,887	[3]	21,837	[3]
Decommissioning costs
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	10 years
Regulatory Assets	13,702		12,484		0
Other regulatory assets
Schedule Of Regulatory Assets And Liabilities [Line Items]
Maximum Amortization Period	15 years
Regulatory Assets	$13,242	[1]	$12,454	[1]	$10,181	[1]
[1]	Recovery of costs, but we are not allowed a rate of return.
[2]	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.
[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 March 31, 2014 is due to 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.

Materials_Supplies_and_Fuel_Ma1

Materials, Supplies and Fuel: Materials, Supplies and Fuel (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified
Inventory, Net [Abstract]
Materials and supplies	$52,429	$49,555	$50,727
Fuel - Electric Utilities	6,780	6,637	7,218
Natural gas in storage held for distribution	7,417	34,999	8,242
Total materials, supplies and fuel	$66,626	$91,191	$66,187

Earnings_Per_Share_Earnings_Pe1

Earnings Per Share: Earnings Per Share (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income (loss) available for common stock	$47,894	$48,118
Weighted average shares - basic	44,541	44,330
Dilutive effect of:
Equity compensation	119	224
Weighted average shares - diluted	44,660	44,554

Earnings_Per_Share_Antidilutiv

Earnings Per Share: Anti-dilutive shares (Details)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares	107	46
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares	107	46

Notes_Payable_and_Longterm_Deb2

Notes Payable and Long-term Debt: Notes Payable (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Revolving Credit Facility [Line Items]
Balance Outstanding	$102,600,000	$75,000,000	$100,000,000
Revolving Credit Facility [Member]
Revolving Credit Facility [Line Items]
Balance Outstanding	102,600,000	75,000,000	100,000,000
Letters of Credit	22,300,000	35,000,000	27,700,000
Current Borrowing Capacity	500,000,000
Expiration Date	29-May-19
Maximum Borrowing Capacity	$750,000,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.18%
Debt Covenants Disclosure [Abstract]
Covenant Requirement - Recourse Leverage Ratio, Actual	55.00%
Covenant Requirement - Recourse Leverage Ratio, Maximum	65.00%
Revolving Credit Facility [Member] | Base Rate [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	0.13%
Revolving Credit Facility [Member] | Eurodollar [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	1.13%
Revolving Credit Facility [Member] | Letter of Credit [Member]
Revolving Credit Facility [Line Items]
Interest Rate at Period End	1.13%

Notes_Payable_and_Longterm_Deb3

Notes Payable and Long-term Debt: Refinancing of Debt (Details) (Black Hills Corporation [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Apr. 13, 2015	Mar. 31, 2015
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] | Subsequent Event [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] | Subsequent Event [Member]
Debt Instrument [Line Items]
Additional debt used for general corporate purposes	25
Corporate Debt Securities [Member] | Corporate Term Loan Due April 2017 [Member] | Subsequent Event [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	300
Debt Instrument, Maturity Date	12-Apr-17

Risk_Management_Activities_Ris1

Risk Management Activities: Risk Management Activities (Details) (USD $)	3 Months Ended				12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Derivative [Line Items]
Derivative assets, current	$0		$1,846,000		$0
Derivative liabilities, current	3,342,000		3,498,000		3,340,000
Derivative liabilities, non-current	2,143,000		4,805,000		2,680,000
Oil and Gas [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	9,900,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative liabilities, current	3,342,000		3,498,000		3,340,000
Derivative liabilities, non-current	2,143,000		4,805,000		2,680,000
Notional Amount	75,000,000	[1]	75,000,000	[1]	75,000,000	[1]
Weighted average fixed interest rate	4.97%		4.97%		4.97%
Maximum Term	1 year 9 months		2 years 9 months		2 years
Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	-3,300,000
Crude Oil [Member] | Swaps and Options [Member] | Oil and Gas [Member]
Derivative [Line Items]
Notional amount - commodities	305,000	[2]	442,500	[2]	334,500	[2]
Maximum Term Hedged in Cash Flow Hedge	1 month	[3]	1 month	[3]	1 month	[3]
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	5,367,500	[2]	8,296,250	[2]	6,582,500	[2]
Maximum Term Hedged in Cash Flow Hedge	1 month	[3]	1 month	[3]	1 month	[3]
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		1,846,000		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	$21,606,000		$4,420,000		$18,740,000
Utilities Group [Member] | Natural Gas, Distribution [Member] | Future [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities	17,280,000		16,140,000		19,370,000
Maximum Term	69 months	[4]	80 months	[4]	72 months	[4]
Utilities Group [Member] | Natural Gas, Distribution [Member] | Commodity Option [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities	1,320,000		1,320,000		4,020,000
Maximum Term	12 months	[4]	12 months	[4]	8 months	[4]
Utilities Group [Member] | Natural Gas, Distribution [Member] | Basis Swap [Member] | Purchase Contract [Member]
Derivative [Line Items]
Notional amount - commodities	15,735,000		14,575,000		12,005,000
Maximum Term	57 months	[4]	69 months	[4]	60 months	[4]
[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 $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	$2,878	($3,564)
Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)	-2,495	-1,205
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0	0
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	-886	-91
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	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)	1,437	-894
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI Derivative (Effective Portion)	3,764	-3,473
Commodity Contract [Member] | Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Reclassified Gain/(Loss) from AOCI into Income (Effective Portion)	-3,932	-311
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	$0	$0

Fair_Value_Measurements_Fair_V1

Fair Value Measurements: Fair Value Measurements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified
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	-15,806	-17,546	-1,877
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	-22,260	-19,776	-11,016
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	15,806	17,546	3,723
Derivative Liabilities, Total	27,745	25,796	19,319
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	5,485	6,020	8,303
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	5,485	6,020	8,303
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	-8,096	-8,599	-7
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	-2	0	-1,983
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	8,096	8,599	7
Derivative Liabilities, Fair Value Disclosure	2	0	1,983
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	-6,526	-6,558	-490
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	-256	-473	-2,114
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	6,526	6,558	490
Derivative Liabilities, Fair Value Disclosure	256	473	2,114
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	-1,184	-2,389	-1,380
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	-22,002	-19,303	-6,919
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	1,184	2,389	3,226
Derivative Liabilities, Fair Value Disclosure	22,002	19,303	6,919
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	1,846
Derivative Liabilities, Total	5,485	6,020	8,303
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	1,846
Derivative Liabilities, Fair Value Disclosure	$0	$0	$0

Fair_Value_Measurements_Balanc

Fair Value Measurements: Balance Sheet Location (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified
Designated as Hedging Instrument [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	$14,622	$15,157	$496
Derivative Liability, Fair Value, Net	5,743	6,493	12,400
Not Designated as Hedging Instrument [Member]
Derivatives, Carrying Amount and Fair Value [Line Items]
Derivative Asset, Fair Value, Net	0	0	1,846
Derivative Liability, Fair Value, Net	20,818	16,914	5,539
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	9,989	10,391	30
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	4,633	4,766	466
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	126	185	3,187
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	132	288	910
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	1,846
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	7,530	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	13,288	8,882	5,539
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	3,342	3,340	3,498
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	2,143	2,680	4,805
Interest Rate Swap [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
Derivative Liability, Fair Value, Gross Liability			0
Interest Rate Swap [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
Derivative Liability, Fair Value, Gross Liability			$0

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments: Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$63,385		$21,218		$17,641		$7,841
Restricted cash and equivalents	2,191		2,056		2
Notes payable	102,600		75,000		100,000
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	63,385		21,218		17,641
Restricted cash and equivalents	2,191		2,056		2
Notes payable	102,600		75,000		100,000
Long-term debt, including current maturities	1,542,658		1,542,589		1,396,949
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Fair Value	63,385	[1]	21,218	[1]	17,641	[1]
Restricted Cash Fair Value Disclosure	2,191	[1]	2,056	[1]	2	[1]
Notes payable, Fair Value	102,600	[1]	75,000	[1]	100,000	[1]
Long-term debt, including current maturities, Fair Value	$1,767,113	[2]	$1,734,555	[2]	$1,541,727	[2]
[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_Los2

Other Comprehensive Income (Loss): Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$19,910	$17,860
Revenue	441,987	460,169
Utilities - Operating and maintenance	71,084	71,227
Non-regulated energy operations and maintenance	22,050	22,332
Income (loss) before earnings (loss) of unconsolidated subsidiaries and income taxes	73,311	73,485
Income tax benefit (expense)	-25,120	-25,366
Cash Flow Hedging [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	-2,495	1,205
Income tax benefit (expense)	1,254	-425
Net income (loss) available for common stock	-1,241	780
Cash Flow Hedging [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	1,437	894
Cash Flow Hedging [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Commodity Contract [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Revenue	-3,932	311
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	-27	-25
Non-regulated energy operations and maintenance	-28	12
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	157
Non-regulated energy operations and maintenance	251	85
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	229
Income tax benefit (expense)	-228	-81
Net income (loss) available for common stock	$422	$148

Other_Comprehensive_Income_Los3

Other Comprehensive Income (Loss): Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	($15,044)	($17,422)
Other comprehensive income (loss), net of tax	990	-1,167
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	-14,054	-18,589
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	5,093	-7,133
Other comprehensive income (loss), net of tax	595	-1,478
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	5,688	-8,611
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	-20,137	-10,289
Other comprehensive income (loss), net of tax	395	311
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	($19,742)	($9,978)

Supplemental_Disclosure_of_Cas2

Supplemental Disclosure of Cash Flow Information: Supplemental Disclosure of Cash Flow Information (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Non-cash Investing and Financing Activities from Continuing Operations [Abstract]
Property, plant and equipment acquired with accrued liabilities	$33,534	$40,939
Increase (decrease) in capitalized assets associated with asset retirement obligations	0	-2,785
Supplemental Cash Flow Elements [Abstract]
Interest (net of amounts capitalized)	-10,909	-11,452
Income taxes, net	($2)	$4

Employee_Benefit_Plans_Employe1

Employee Benefit Plans: Employee Benefit Plans (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$1,494	$1,362
Interest cost	3,880	3,963
Expected return on plan assets	-4,867	-4,516
Prior service cost (benefit)	15	16
Net loss (gain)	2,759	1,201
Net periodic benefit cost	3,281	2,026
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	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
Interest cost	450	479
Expected return on plan assets	-33	-21
Prior service cost (benefit)	-107	-107
Net loss (gain)	102	40
Net periodic benefit cost	876	816
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	939
Estimated Future Employer Contributions in Current Fiscal Year	2,816
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	491	374
Interest cost	364	362
Prior service cost (benefit)	1	1
Net loss (gain)	270	124
Net periodic benefit cost	1,126	861
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions by Employer	372
Estimated Future Employer Contributions in Current Fiscal Year	1,115
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], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
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_Contingencies_1

Commitments and Contingencies: Commitments and Contingencies - Dividend Restrictions (Details) (Utilities Group [Member], USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Utilities Group [Member]
Related Party Transaction [Line Items]
Restricted Net Assets for Subsidiaries	$338