Energen (EGN) 10-Q 11 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 01, 2014
Entity Information	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Entity Registrant Name	'ENERGEN CORP	'
Entity Central Index Key	'0000277595	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	73,194,619
Alabama Gas Corporation	'	'
Entity Information	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Entity Registrant Name	'ALABAMA GAS CORP	'
Entity Central Index Key	'0000003146	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	1,972,052

Consolidated_Condensed_Balance

Consolidated Condensed Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets	'	'
Cash and cash equivalents	$1,516	$2,523
Short-term investments	42,000	0
Accounts receivable	'	'
Allowance for doubtful accounts	-676	-696
Accounts receivable, net of allowance for doubtful accounts of $676 and $696 at June 30, 2014 and December 31, 2013, respectively	178,721	136,334
Inventories	'	'
Inventory, Net	12,541	11,130
Assets held for sale with prior period comparable	1,154,046	1,242,872
Deferred income taxes	49,580	21,250
Derivative instruments	524	17,463
Prepayments and other	37,937	9,989
Total current assets	1,476,865	1,441,561
Oil and Gas Property, Successful Effort Method, Net [Abstract]	'	'
Proved properties	7,273,932	6,695,400
Unproved properties	170,736	168,975
Less accumulated depreciation, depletion and amortization	2,030,941	1,776,802
Oil and natural gas properties, net	5,413,727	5,087,573
Other property and equipment, net	37,869	30,515
Total property, plant and equipment, net	5,451,596	5,118,088
Other Assets	'	'
Other postretirement assets	4,592	8,894
Noncurrent derivative instruments	623	5,439
Other assets	48,433	48,230
TOTAL ASSETS	6,982,109	6,622,212
Current Liabilities	'	'
Long-term debt due within one year	570,000	60,000
Notes payable to banks	669,000	489,000
Accounts payable	135,416	78,178
Accrued taxes	21,029	8,201
Accrued wages and benefits	26,979	27,036
Accrued capital costs	92,740	93,623
Revenue and royalty payable	66,071	51,519
Liabilities related to assets held for sale with prior period comparable	767,131	831,570
Derivative instruments	96,213	30,302
Other	20,159	21,796
Total current liabilities	2,464,738	1,691,225
Deferred Credits and Other Liabilities	'	'
Long-term debt	553,552	1,093,541
Asset retirement obligations	113,087	108,533
Pension liabilities	51,475	47,484
Deferred income taxes	848,422	807,614
Noncurrent derivative instruments	21,705	398
Other long-term liabilities	15,113	15,398
Total liabilities	4,068,092	3,764,193
Commitments and Contingencies	'	'
Shareholders’ Equity	'	'
Preferred stock, cumulative, $0.01 par value, 5,000,000 shares authorized	0	0
Common shareholders’ equity	'	'
Common stock, $0.01 par value; 150,000,000 shares authorized; 76,080,876 shares and 75,574,156 shares issued at June 30, 2014 and December 31, 2013, respectively	761	756
Premium on capital stock	558,037	523,711
Retained earnings	2,500,116	2,476,616
Accumulated other comprehensive income (loss), net of tax	'	'
Unrealized gain on hedges, net	7,304	13,362
Pension and postretirement plans	-27,642	-32,245
Interest rate swap	-161	-1,184
Deferred compensation plan	3,270	3,259
Treasury stock, at cost; 2,978,179 shares and 2,967,999 shares at June 30, 2014 and December 31, 2013, respectively	-127,668	-126,256
Total shareholders’ equity	2,914,017	2,858,019
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	6,982,109	6,622,212
Alabama Gas Corporation	'	'
Current Assets	'	'
Cash and cash equivalents	11,807	3,032
Accounts receivable	'	'
Gas	49,938	103,301
Other	5,347	5,447
Affiliated companies	13,172	4,662
Allowance for doubtful accounts	-5,000	-5,000
Inventories	'	'
Storage gas inventory	31,975	32,095
Materials and supplies	5,098	5,471
Liquified natural gas in storage	2,877	3,634
Regulatory assets	2,316	2,756
Income tax receivable	0	3,644
Deferred income taxes	21,095	20,049
Prepayments and other	987	4,654
Total current assets	139,612	183,745
Oil and Gas Property, Successful Effort Method, Net [Abstract]	'	'
Utility plant	1,517,534	1,491,433
Less accumulated depreciation	624,704	605,924
Utility plant, net	892,830	885,509
Other property and equipment, net	40	41
Other Assets	'	'
Regulatory asset	91,857	84,890
Other postretirement assets	28,985	26,457
Other assets	21,830	17,433
Total other assets	142,672	128,780
TOTAL ASSETS	1,175,154	1,198,075
Current Liabilities	'	'
Long-term debt due within one year	50,000	0
Notes payable to banks	0	50,000
Accounts payable	38,646	48,653
Accrued taxes	37,273	28,027
Customers’ deposits	20,102	21,692
Amounts due customers	9,556	16,990
Accrued wages and benefits	4,519	7,682
Regulatory liabilities	64,401	49,006
Other	10,055	10,113
Total current liabilities	234,552	232,163
Deferred Credits and Other Liabilities	'	'
Long-term debt	199,830	249,923
Pension liabilities	28,479	20,191
Regulatory liabilities	82,580	94,125
Deferred income taxes	208,171	205,631
Other long-term liabilities	16,139	11,462
Total Deferred Credits and Other Liabilities	335,369	331,409
Commitments and Contingencies	'	'
Shareholders’ Equity	'	'
Preferred stock, cumulative, $0.01 par value, 5,000,000 shares authorized	0	0
Common shareholders’ equity	'	'
Common stock, $0.01 par value; 150,000,000 shares authorized; 76,080,876 shares and 75,574,156 shares issued at June 30, 2014 and December 31, 2013, respectively	20	20
Premium on capital stock	31,682	31,682
Capital surplus	2,802	2,802
Retained earnings	370,899	350,076
Accumulated other comprehensive income (loss), net of tax	'	'
Total shareholders’ equity	405,403	384,580
Total capitalization	605,233	634,503
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$1,175,154	$1,198,075

Consolidated_Condensed_Balance1

Consolidated Condensed Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Current Assets	'	'
Allowance for doubtful accounts	$676	$696
Shareholders’ Equity	'	'
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	76,080,876	75,574,156
Treasury stock, shares	2,978,179	2,967,999
Alabama Gas Corporation	'	'
Current Assets	'	'
Allowance for doubtful accounts	$5,000	$5,000
Shareholders’ Equity	'	'
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	120,000	120,000
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	3,000,000	3,000,000
Common stock, shares issued	1,972,052	1,972,052

Consolidated_Condensed_Stateme

Consolidated Condensed Statements of Income (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues	'	'	'	'
Oil, natural gas liquids and natural gas sales	$355,852	$312,400	$706,674	$567,239
Gain (loss) on derivative instruments, net	-84,846	55,244	-138,237	36,288
Loss on sale of assets and other	-909	-663	-1,062	-215
Total revenues	270,097	366,981	567,375	603,312
Operating Costs and Expenses	'	'	'	'
Oil, natural gas liquids and natural gas production	64,697	59,607	132,141	125,149
Production and ad valorem taxes	28,049	23,503	55,373	46,879
Depreciation, depletion and amortization	136,244	112,384	260,464	207,336
Exploration	2,575	3,455	15,389	4,953
General and administrative	33,542	27,666	65,715	55,752
Income taxes	'	'	'	'
Deferred	'	'	16,551	57,500
Accretion of discount on asset retirement obligations	1,883	1,729	3,726	3,416
Total costs and expenses	266,990	228,344	532,808	443,485
Operating Income	3,107	138,637	34,567	159,827
Other Income (Expense)	'	'	'	'
Interest expense	-7,964	-10,182	-15,852	-20,083
Other income	687	196	1,010	1,370
Total other expense	-7,277	-9,986	-14,842	-18,713
Interest Expense	'	'	'	'
Income (Loss) From Continuing Operations Before Income Taxes	-4,170	128,651	19,725	141,114
Income tax expense (benefit)	-1,016	46,229	7,232	50,273
Income (Loss) From Continuing Operations	-3,154	82,422	12,493	90,841
Discontinued Operations, net of tax	'	'	'	'
Income (loss) from discontinued operations	-4,799	645	33,920	48,918
Loss on disposal of discontinued operations	0	0	-1,050	0
Total Income (Loss) From Discontinued Operations	-4,799	645	32,870	48,918
Net Income (Loss)	-7,953	83,067	45,363	139,759
Diluted Earnings Per Average Common Share	'	'	'	'
Continuing Operations (in dollars per share)	($0.04)	$1.14	$0.17	$1.26
Discontinued operations (in dollars per share)	($0.07)	$0.01	$0.45	$0.67
Diluted Earnings Per Average Common Share (in dollars per share)	($0.11)	$1.15	$0.62	$1.93
Basic Earnings Per Average Common Share	'	'	'	'
Continuing Operations (in dollars per share)	($0.04)	$1.14	$0.17	$1.26
Discontinued operations (in dollars per share)	($0.07)	$0.01	$0.45	$0.68
Net Income (Loss) (in dollars per share)	($0.11)	$1.15	$0.62	$1.94
Dividends Per Common Share	$0.15	$0.14	$0.30	$0.29
Diluted Average Common Shares Outstanding	72,851	72,419	73,031	72,329
Basic Average Common Shares Outstanding	72,851	72,167	72,737	72,155
Alabama Gas Corporation	'	'	'	'
Revenues	'	'	'	'
Operating Revenues	93,873	104,514	357,774	342,199
Operating Costs and Expenses	'	'	'	'
Cost of gas	38,468	47,571	166,582	143,013
Operations and maintenance	34,771	36,005	70,995	74,022
Depreciation, depletion and amortization	11,445	10,873	22,770	21,602
Income taxes	'	'	'	'
Current	-687	-1,778	24,530	24,143
Deferred	227	1,335	1,494	4,355
Taxes, other than income taxes	7,243	7,846	23,130	22,050
Total costs and expenses	91,467	101,852	309,501	289,185
Operating Income	2,406	2,662	48,273	53,014
Other Income (Expense)	'	'	'	'
Interest expense	-3,745	-3,833	-7,710	-7,863
Allowance for funds used during construction	62	227	135	446
Other income	1,090	361	2,598	1,111
Other expense	-428	-121	-883	-190
Total other expense	724	467	1,850	1,367
Interest Expense	'	'	'	'
Interest on long-term debt	3,375	3,377	6,752	6,755
Other interest expense	370	456	958	1,108
Discontinued Operations, net of tax	'	'	'	'
Net Income (Loss)	($615)	($704)	$42,413	$46,518

Consolidated_Condensed_Stateme1

Consolidated Condensed Statements of Comprehensive Income (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net Income (Loss)	($7,953)	$83,067	$45,363	$139,759
Other comprehensive income (loss):	'	'	'	'
Total cash flow hedges	-2,698	13,659	-5,035	-23,611
Pension and postretirement plans:	'	'	'	'
Amortization of net benefit obligation at transition, net of tax of $3, $26, $7 and $52, respectively	6	47	12	95
Amortization of prior service cost, net of tax of $26, $28, $52 and $55, respectively	48	51	96	102
Amortization of net loss, including settlement charges, net of tax of $577, $734, $3,571 and $1,654, respectively	1,072	1,363	6,631	3,071
Current period change in fair value of pension and postretirement plans, net of tax of ($1,151) and $0, respectively	-2,136	0	-2,136	0
Total pension and postretirement plans	-1,010	1,461	4,603	3,268
Comprehensive Income (Loss)	-11,661	98,187	44,931	119,416
Inventories	'	'	-1,411	8,038
Commodity contracts	'	'	'	'
Other comprehensive income (loss):	'	'	'	'
Current period change in fair value of derivative commodity instruments, net of tax of $6, $9,713, $7 and ($6,712), respectively	9	15,847	11	-10,951
Reclassification adjustment for derivative commodity instruments, net of tax of ($2,179), ($1,711), ($3,720) and ($8,281), respectively	-3,556	-2,792	-6,069	-13,511
Current period change in fair value of interest rate swap, net of tax of ($98), $176, ($160) and $165, respectively	9	15,847	11	-10,951
Reclassification adjustment for interest rate swap, net of tax of $556, $149, $712 and $292, respectively	-3,556	-2,792	-6,069	-13,511
Interest rate swap	'	'	'	'
Other comprehensive income (loss):	'	'	'	'
Current period change in fair value of derivative commodity instruments, net of tax of $6, $9,713, $7 and ($6,712), respectively	-183	327	-298	307
Reclassification adjustment for derivative commodity instruments, net of tax of ($2,179), ($1,711), ($3,720) and ($8,281), respectively	1,032	277	1,321	544
Current period change in fair value of interest rate swap, net of tax of ($98), $176, ($160) and $165, respectively	-183	327	-298	307
Reclassification adjustment for interest rate swap, net of tax of $556, $149, $712 and $292, respectively	$1,032	$277	$1,321	$544

Consolidated_Condensed_Stateme2

Consolidated Condensed Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amortization of net obligation at transition, tax	$3	$26	$7	$52
Amortization of prior service cost, tax	26	28	52	55
Amortization of net loss, including settlement charges, tax	577	734	3,571	1,654
Current period change in fair value of pension, tax	-1,151	0	-1,151	0
Commodity contracts	'	'	'	'
Current period change in fair value of interest rate swap, tax	6	9,713	7	-6,712
Reclassification adjustment for derivative instruments, tax	-2,179	-1,711	-3,720	-8,281
Interest rate swap	'	'	'	'
Current period change in fair value of interest rate swap, tax	-98	176	-160	165
Reclassification adjustment for derivative instruments, tax	$556	$149	$712	$292

Consolidated_Condensed_Stateme3

Consolidated Condensed Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating Activities	'	'
Net Income (Loss)	$45,363	$139,759
Income from discontinued operations	-32,870	-48,918
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	260,464	207,336
Accretion of discount on asset retirement obligations	3,726	3,416
Deferred income taxes	16,551	57,500
Change in derivative fair value	103,270	-19,143
(Gain) loss on sale of assets	131	-105
Stock-based compensation expense	9,012	7,766
Exploration, including dry holes	3,874	937
Discontinued operations	122,199	152,700
Other, net	7,675	21,210
Net change in:	'	'
Accounts receivable	-46,884	-25,990
Inventories	-1,411	8,038
Accounts payable	60,617	19,802
Pension and other postretirement benefit contributions	-2,323	-5,153
Other current assets and liabilities	-6,919	20,639
Net cash provided by operating activities	542,475	539,794
Investing Activities	'	'
Additions to oil and natural gas properties	-575,049	-621,698
Net increases (decreases) in advances from affiliates	-8,510	2,378
Acquisitions, net of cash acquired	-22,114	-17,183
Proceeds from sale of assets	217	2,382
Purchase of short-term investments	-191,000	0
Sale of short-term investments	149,000	0
Discontinued operations	-690	-45,178
Other, net	69	-260
Net cash used in investing activities	-639,567	-681,937
Financing Activities	'	'
Payment of dividends on common stock	-21,863	-20,945
Issuance of common stock	23,053	108
Reduction of long-term debt	-30,000	0
Net change in short-term debt	180,000	234,000
Tax benefit on stock compensation	3,763	79
Discontinued operations	-50,093	-77,010
Net cash provided by financing activities	104,860	136,232
Net increase (decrease) in cash and cash equivalents	7,768	-5,911
Cash and Cash Equivalents, at Carrying Value, Including Discontinued Operations	5,555	9,704
Cash and cash equivalents at beginning of period	2,523	'
Cash and Cash Equivalents, at Carrying Value, Including Discontinued Operations	13,323	3,793
Less cash and cash equivalents of discontinued operations at end of period	-11,807	-565
Cash and cash equivalents at end of period	1,516	3,228
Alabama Gas Corporation	'	'
Operating Activities	'	'
Net Income (Loss)	42,413	46,518
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	22,770	21,602
Deferred income taxes	1,494	4,355
Bad debt expense	910	450
Gain on sale of assets	-703	0
Other, net	-141	7,083
Net change in:	'	'
Accounts receivable	15,172	8,179
Inventories	1,250	11,512
Accounts payable	-7,185	-6,828
Amounts due customers, including gas supply pass-through	33,839	26,797
Income tax receivable	3,644	2,762
Pension and other postretirement benefit contributions	-1,590	-5,600
Other current assets and liabilities	8,101	16,863
Net cash provided by operating activities	119,974	133,693
Investing Activities	'	'
Additions to oil and natural gas properties	-31,703	-44,679
Proceeds from sale of assets	797	0
Other, net	-100	-500
Net cash used in investing activities	-39,516	-42,801
Financing Activities	'	'
Payment of dividends on common stock	-21,590	-18,876
Reduction of long-term debt	-93	-10
Net change in short-term debt	-50,000	-77,000
Net cash provided by financing activities	-71,683	-95,886
Net increase (decrease) in cash and cash equivalents	8,775	-4,994
Cash and cash equivalents at beginning of period	3,032	5,559
Cash and cash equivalents at end of period	$11,807	$565

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2014
Organization and Basis of Presentation	'
	ORGANIZATION AND BASIS OF PRESENTATION
	Energen Corporation (Energen or the Company) is an oil and gas exploration and production company primarily engaged in the exploration, development and production of oil and gas properties in the Permian Basin in west Texas and in the San Juan Basin in New Mexico and Colorado in the continental United States. Our operations are conducted substantially through our subsidiary Energen Resources Corporation (Energen Resources). Energen is currently complemented by its legacy natural gas distribution business, Alabama Gas Corporation (Alagasco), which is engaged in the purchase, distribution and sale of natural gas principally in central and north Alabama. The unaudited consolidated financial statements and notes should be read in conjunction with the financial statements and notes thereto for the years ended December 31, 2013, 2012 and 2011, included in the 2013 Annual Report of Energen and Alagasco on Form 10-K.
	Our accompanying unaudited consolidated financial statements include Energen and its subsidiaries and have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the disclosures required for complete financial statements. Results of operations for interim periods are not necessarily indicative of the results that may be expected for the year. In the opinion of management, the accompanying financial statements reflect all adjustments necessary to present fairly our financial position, results of operations, and cash flows for the periods and as of the dates shown. Such adjustments consist of normal recurring items. In addition, and in connection with the pending sale of Alagasco, we have chosen to reformat our financial statements to reflect a presentation more closely aligned with our peers in the oil and gas industry. As part of the financial statement reformatting, certain reclassifications were made to conform prior periods’ financial statements to the current-quarter presentation. These reclassifications primarily included further detail under operating costs and expenses. We further reclassified all commodity hedges from oil and natural gas operating revenues to gain (loss) on derivative instruments, net, as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Open non-cash mark-to-market gains (losses) on derivative instruments	$	(59,621	)	$	56,149		$	(93,302	)	$	15,101
	Closed gains (losses) on derivative instruments	$	(25,225	)	$	(905	)	$	(44,935	)	$	21,187
	Gain (loss) on derivative instruments, net	$	(84,846	)	$	55,244		$	(138,237	)	$	36,288
	In April 2014, Energen signed a stock purchase agreement to sell Alagasco to The Laclede Group, Inc. (Laclede) for $1.6 billion, subject to closing adjustments, which includes an estimated $1.28 billion in cash and the assumption of $320 million in debt. This sale is expected to close during 2014. Energen plans to use cash proceeds from the sale to reduce long-term and short-term indebtedness. During the second quarter of 2014, Energen classified Alagasco as held for sale with prior period comparable and reflected the associated operating results in discontinued operations. See Note 13, Discontinued Operations, for further information regarding the pending sale of Alagasco.
	We classified as discontinued operations interest on debt required to be extinguished, certain depreciation costs that end at close, the related income tax impact of these items and the earnings of Alagasco. In addition, we reclassified from discontinued operations certain general and administrative costs, other income and the related tax impact from these items. The table below provides a detail of these items included in income (loss) from discontinued operations at June 30, 2014:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Alagasco net income (loss)	$	(615	)	$	(704	)	$	42,413		$	46,518
	Depreciation, depletion and amortization	(153		)	(147		)	(305		)	(294		)
	General and administrative	687			1,724			1,627			3,578
	Interest expense	(7,190		)	(3,288		)	(12,977		)	(6,109		)
	Other income	(228		)	(64		)	(347		)	(473		)
	Income tax expense (benefit)	2,603			671			4,538			1,247
	Alagasco income (loss) from discontinued operations	(4,896		)	(1,808		)	34,949			44,467
	Energen income (loss) from discontinued operations	97			2,453			(1,029		)	4,451
	Income (loss) from discontinued operations	$	(4,799	)	$	645		$	33,920		$	48,918
Alabama Gas Corporation	'
Organization and Basis of Presentation	'
	BASIS OF PRESENTATION
	Alabama Gas Corporation (Alagasco) is a wholly owned subsidiary of Energen Corporation. Alagasco has a September 30 fiscal year for rate-setting purposes (rate year) and reports on a calendar year for the Securities and Exchange Commission and all other financial accounting reporting purposes. The accompanying unaudited financial statements and notes should be read in conjunction with the financial statements and notes thereto for the years ended December 31, 2013, 2012 and 2011, included in the 2013 Annual Report of Energen Corporation (Energen) and Alabama Gas Corporation on Form 10-K and have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the disclosures required for complete financial statements. Alagasco’s natural gas distribution business is seasonal in character and influenced by weather conditions, and therefore, the results of operations for interim periods are not necessarily indicative of the results that may be expected for the year. All adjustments to the unaudited financial statements that are, in the opinion of management, necessary for a fair statement of the results for the interim periods have been recorded. Such adjustments consist of normal recurring items. Certain reclassifications were made to conform prior years’ financial statements to the current-quarter presentation.
	In April 2014, Energen signed a stock purchase agreement to sell Alagasco to The Laclede Group, Inc. (Laclede) for $1.6 billion, subject to closing adjustments, which includes an estimated $1.28 billion in cash and the assumption of $320 million in debt. This sale is expected to close during 2014. Energen plans to use cash proceeds from the sale to reduce long-term and short-term indebtedness.

Regulatory_Matters

Regulatory Matters	6 Months Ended
	Jun. 30, 2014
Regulatory Matters [Line Items]	'
Regulatory Matters	'
	REGULATORY MATTERS
	Alagasco is subject to regulation by the Alabama Public Service Commission (APSC) which established the Rate Stabilization and Equalization (RSE) rate-setting process in 1983. Alagasco’s current RSE order has a term extending through September 30, 2018 and will continue beyond September 30, 2018, unless the APSC enters an order to the contrary in a manner consistent with law. In the event of unforeseen circumstances, whether physical or economic, of the nature of force majeure and including a change in control, the APSC and Alagasco will consult in good faith with respect to modifications, if any. Effective January 1, 2014, Alagasco’s allowed range of return on average common equity is 10.5 percent to 10.95 percent with an adjusting point of 10.8 percent. Alagasco is eligible to receive a performance-based adjustment of 5 basis points to the return on equity adjusting point, based on meeting certain customer satisfaction criteria. Under RSE, the APSC conducts quarterly reviews to determine whether Alagasco’s return on average common equity at the end of the rate year will be within the allowed range of return. Reductions in rates can be made quarterly to bring the projected return within the allowed range; increases, however, are allowed only once each rate year, effective December 1, and cannot exceed 4 percent of prior-year revenues. During the three months and six months ended June 30, 2014, Alagasco had net pre-tax reductions in revenues of $4.0 million and $20.3 million, respectively, to bring the return on average common equity to midpoint within the allowed range of return. During the three months and six months ended June 30, 2013, Alagasco had net pre-tax reductions in revenues of $3.8 million and $6.3 million, respectively, to bring the return on average common equity to midpoint within the allowed range of return. Under the provisions of RSE, an $8.5 million decrease, $10.3 million increase and $7.8 million increase in revenues became effective January 1, 2014, December 1, 2013 and 2012, respectively. The equity upon which a return will be permitted cannot exceed 56.5 percent of total capitalization, subject to certain adjustments. The APSC approved the sale of Alagasco to Laclede, and the order for approval to transfer one hundred percent ownership of common stock of Alagasco from Energen to Laclede was signed on July 24, 2014. This sale is expected to close during 2014.
	Alagasco’s rate schedules for natural gas distribution charges contain a Gas Supply Adjustment (GSA) rider, established in 1993, which permits the pass-through to customers of changes in the cost of gas supply. Alagasco’s tariff provides a temperature adjustment mechanism, also included in the GSA, which is designed to moderate the impact of departures from normal temperatures on Alagasco’s earnings. The temperature adjustment applies primarily to residential, small commercial and small industrial customers. Other non-temperature weather related conditions that may affect customer usage are not included in the temperature adjustment.
Alabama Gas Corporation	'
Regulatory Matters [Line Items]	'
Regulatory Matters	'
	REGULATORY MATTERS
	Alagasco is subject to regulation by the Alabama Public Service Commission (APSC) which established the Rate Stabilization and Equalization (RSE) rate-setting process in 1983. Alagasco’s current RSE order has a term extending through September 30, 2018 and will continue beyond September 30, 2018, unless the APSC enters an order to the contrary in a manner consistent with law. In the event of unforeseen circumstances, whether physical or economic, of the nature of force majeure and including a change in control, the APSC and Alagasco will consult in good faith with respect to modifications, if any. Effective January 1, 2014, Alagasco’s allowed range of return on average common equity is 10.5 percent to 10.95 percent with an adjusting point of 10.8 percent. The previous allowed range of return on average common equity was 13.15 percent to 13.65 percent through December 31, 2013. Alagasco is eligible to receive a performance-based adjustment of 5 basis points to the return on equity adjusting point, based on meeting certain customer satisfaction criteria. Under RSE, the APSC conducts quarterly reviews to determine whether Alagasco’s return on average common equity at the end of the rate year will be within the allowed range of return. Reductions in rates can be made quarterly to bring the projected return within the allowed range; increases, however, are allowed only once each rate year, effective December 1, and cannot exceed 4 percent of prior-year revenues. During the three months and six months ended June 30, 2014, Alagasco had net pre-tax reductions in revenues of $4.0 million and $20.3 million, respectively, to bring the return on average common equity to midpoint within the allowed range of return. During the three months and six months ended June 30, 2013, Alagasco had net pre-tax reductions in revenues of $3.8 million and $6.3 million, respectively, to bring the return on average common equity to midpoint within the allowed range of return. Under the provisions of RSE, an $8.5 million decrease, $10.3 million increase and $7.8 million increase in revenues became effective January 1, 2014, December 1, 2013 and 2012, respectively. The equity upon which a return will be permitted cannot exceed 56.5 percent of total capitalization, subject to certain adjustments. The APSC approved the sale of Alagasco to Laclede, and the order for approval to transfer one hundred percent ownership of common stock of Alagasco from Energen to Laclede was signed on July 24, 2014. This sale is expected to close during 2014.
	The inflation-based Cost Control Mechanism (CCM), established by the APSC, allows for annual increases to operations and maintenance (O&M) expense. The CCM range is Alagasco’s 2007 actual rate year O&M expense (Base Year) inflation-adjusted using the June Consumer Price Index For All Urban Consumers each rate year plus or minus 1.75 percent (Index Range). If rate year O&M expense falls within the Index Range, no adjustment is required. If rate year O&M expense exceeds the Index Range, three-quarters of the difference is returned to customers through future rate adjustments. To the extent that rate year O&M is less than the Index Range, the utility benefits by one-half of the difference through future rate adjustments. Certain items that fluctuate based on situations demonstrated to be beyond Alagasco’s control may be excluded from the CCM calculation. During the second quarter of 2014, Alagasco recorded an increase to revenue of approximately $1.0 million pre-tax to reflect an estimated O&M expense benefit resulting from being below the Index Range. This estimate was based on actual O&M expense through June 2014, and budgeted O&M expense through September 2014.
	Alagasco’s rate schedules for natural gas distribution charges contain a Gas Supply Adjustment (GSA) rider, established in 1993, which permits the pass-through to customers of changes in the cost of gas supply. Alagasco’s tariff provides a temperature adjustment mechanism, also included in the GSA, which is designed to moderate the impact of departures from normal temperatures on Alagasco’s earnings. The temperature adjustment applies primarily to residential, small commercial and small industrial customers. Other non-temperature weather related conditions that may affect customer usage are not included in the temperature adjustment.
	The APSC approved an Enhanced Stability Reserve (ESR) in 1998, which was subsequently modified and expanded in 2010. As currently approved, the ESR provides deferred treatment and recovery for the following: (1) extraordinary O&M expenses related to environmental response costs; (2) extraordinary O&M expenses related to self insurance costs that exceed $1 million per occurrence; (3) extraordinary O&M expenses, other than environmental response costs and self insurance costs, resulting from a single force majeure event or multiple force majeure events greater than $275,000 and $412,500, respectively, during a rate year; and (4) negative individual large commercial and industrial customer budget revenue variances that exceed $350,000 during a rate year. Charges to the ESR are subject to certain limitations which may disallow deferred treatment and which prescribe the timing of recovery. Funding to the ESR is provided as a reduction to the refundable negative salvage balance over its nine year term beginning December 1, 2010. Subsequent to the nine year period and subject to APSC authorization, Alagasco expects to be able to recover underfunded ESR balances over a five year amortization period with an annual limitation of $660,000. Amounts in excess of this limitation are deferred for recovery in future years.

Derivative_Commodity_Instrumen

Derivative Commodity Instruments	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Commodity Instruments	'
	DERIVATIVE COMMODITY INSTRUMENTS
	We periodically enter into derivative commodity instruments to hedge our exposure to price fluctuations on oil, natural gas liquids and natural gas production. Such instruments may include over-the-counter (OTC) swaps and basis swaps typically executed with investment and commercial banks and energy-trading firms. Derivative transactions are pursuant to standing authorizations by the Board of Directors, which do not authorize speculative positions.
	Due to the volatility of commodity prices, the estimated fair value of our derivative instruments is subject to fluctuation from period to period, which could result in significant differences between the current estimated fair value and the ultimate settlement price. Additionally, Energen is at risk of economic loss based upon the creditworthiness of our counterparties. We were in a net gain position with two of our active counterparties and in a net loss position with the remaining twelve at June 30, 2014. The counterparty net gain positions at June 30, 2014 constituted approximately $1.0 million.
	Energen’s current policy is to not enter into agreements that require the posting of collateral. The majority of our counterparty agreements include provisions for net settlement of transactions payable on the same date and in the same currency. Most of the agreements include various contractual set-off rights, which may be exercised by the non-defaulting party in the event of an early termination due to a default.
	Prior to June 30, 2013, Energen used cash flow hedge accounting where applicable for its derivative transactions. The effective portion of the gain or loss on the derivative instrument was recognized in accumulated other comprehensive income as a component of shareholders’ equity and subsequently reclassified as gain (loss) on derivative instruments, net when the forecasted transaction affects earnings. The ineffective portion of a derivative’s change in fair value was required to be recognized immediately in gain (loss) on derivative instruments, net. All other derivative transactions not designated as cash flow hedge accounting are accounted for as mark-to-market transactions with gains or losses recognized in the period of change in gain (loss) on derivative instruments, net.
	Effective March 31, 2013 and June 30, 2013, Energen dedesignated from cash flow hedge accounting 5,078 thousand barrels (MBbl) and 2,353 MBbl, respectively, of various New York Mercantile Exchange (NYMEX) oil contracts associated with the Permian Basin due to lack of correlation. Gains and losses from inception of the hedge to the dedesignation date were frozen and will remain in accumulated other comprehensive income until the forecasted transactions actually occur. Subsequent gains or losses will be accounted for as mark-to-market transactions and recognized immediately through gain (loss) on derivative instruments, net.
	Effective June 30, 2013, Energen elected to discontinue the use of cash flow hedge accounting and to dedesignate all remaining derivative commodity instruments that were previously designated as cash flow hedges. As a result of discontinuing hedge accounting, any gains or losses from inception of the hedge to June 30, 2013 were frozen and will remain in accumulated other comprehensive income until the forecasted transactions actually occur. Any subsequent gains or losses will be accounted for as mark-to-market and recognized immediately through gain (loss) on derivative instruments, net. As a result of Energen’s election to discontinue hedge accounting, all derivative transactions entered into subsequent to June 30, 2013 will be accounted for as mark-to-market transactions with gains or losses recognized in the period of change in gain (loss) on derivative instruments, net.
	The following tables detail the offsetting of derivative assets and liabilities as well as the fair values of derivatives on the balance sheets:
	(in thousands)	30-Jun-14
											Gross Amounts Not Offset in the Balance Sheets
		Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amount Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
	Derivatives not designated as hedging instruments
	Assets
	Derivative instruments	$	14,540		$	(14,016	)	$	524		$	—	$	—	$	524
	Noncurrent derivative instruments	2,076			(1,453		)	623			—		—		623
	Total derivative assets	16,616			(15,469		)	1,147			—		—		1,147
	Liabilities
	Derivative instruments	110,229			(14,016		)	96,213			—		—		96,213
	Noncurrent derivative instruments	23,158			(1,453		)	21,705			—		—		21,705
	Total derivative liabilities	133,387			(15,469		)	117,918			—		—		117,918
	Total derivatives	$	(116,771	)	$	—		$	(116,771	)	$	—	$	—	$	(116,771	)
	(in thousands)	31-Dec-13
											Gross Amounts Not Offset in the Balance Sheets
		Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amount Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
	Derivatives not designated as hedging instruments
	Assets
	Derivative instruments	$	36,223		$	(18,760	)	$	17,463		$	—	$	—	$	17,463
	Noncurrent derivative instruments	7,992			(2,553		)	5,439			—		—		5,439
	Total derivative assets	44,215			(21,313		)	22,902			—		—		22,902
	Liabilities
	Derivative instruments	49,062			(18,760		)	30,302			—		—		30,302
	Noncurrent derivative instruments	2,553			(2,553		)	—			—		—		—
	Total derivative liabilities	51,615			(21,313		)	30,302			—		—		30,302
	Total derivatives	$	(7,400	)	$	—		$	(7,400	)	$	—	$	—	$	(7,400	)
	Energen had a net $4.5 million and a net $8.2 million deferred tax liability included in current deferred income taxes on the balance sheets related to derivative items included in accumulated other comprehensive income as of June 30, 2014, and December 31, 2013, respectively.
	The following table details the effect of derivative commodity instruments in cash flow hedging relationships on the financial statements:
	(in thousands)	Location on Statements of Income	Three months			Three months
			ended			ended
			30-Jun-14			30-Jun-13
	Net gain recognized in other comprehensive income on derivatives (effective portion), net of tax of $6 and $9,713	—	$	9		$	15,847
	Gain reclassified from accumulated other comprehensive income into income (effective portion)	Gain (loss) on derivative instruments, net	$	5,735		$	3,112
	Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	Gain (loss) on derivative instruments, net	$	—		$	1,392
	(in thousands)	Location on Statements of Income	Six months			Six months
			ended			ended
			30-Jun-14			30-Jun-13
	Net gain (loss) recognized in other comprehensive income on derivatives (effective portion), net of tax of $7 and ($6,712)	—	$	11		$	(10,951	)
	Gain reclassified from accumulated other comprehensive income into income (effective portion)	Gain (loss) on derivative instruments, net	$	9,789		$	20,935
	Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	Gain (loss) on derivative instruments, net	$	—		$	858
	The following table details the effect of open and closed derivative commodity instruments not designated as hedging instruments on the income statement:
	(in thousands)	Location on Statements of Income	Three months			Three months
			ended			ended
			30-Jun-14			30-Jun-13
	Gain (loss) recognized in income on derivatives	Gain (loss) on derivative instruments, net	$	(90,581	)	$	53,078
	(in thousands)	Location on Statements of Income	Six months			Six months
			ended			ended
			30-Jun-14			30-Jun-13
	Gain (loss) recognized in income on derivatives	Gain (loss) on derivative instruments, net	$	(148,026	)	$	21,577
	As of June 30, 2014, $7.3 million, net of tax, of deferred net gains on derivative instruments recorded in accumulated other comprehensive income are expected to be reclassified and reported in earnings as revenues during the next twelve-month period. During 2013, we had a discontinuance of hedge accounting when Energen determined it was probable certain forecasted volumes would not occur due to certain properties being sold. This discontinuance of hedge accounting resulted in $3.0 million of after-tax losses being recognized into gain (loss) on derivative instruments, net during the six months ended June 30, 2014.
	As of June 30, 2014, Energen had entered into the following transactions for the remainder of 2014 and subsequent years:
	Production Period	Total Hedged Volumes		Average Contract	Description
				Price
	Oil
	2014	4,958	MBbl	$92.65 Bbl	NYMEX Swaps
2015	8,280	MBbl	$89.30 Bbl	NYMEX Swaps
Oil Basis Differential
2014	600	MBbl	$(3.30) Bbl	WTS/WTI Basis Swaps*
2014	1,200	MBbl	$(3.08) Bbl	WTI/WTI Basis Swaps**
Natural Gas Liquids
2014	35.8	MMgal	$0.93 Gal	Liquids Swaps
Natural Gas
2014	5.2	Bcf	$4.56 Mcf	NYMEX Swaps
2014	15.4	Bcf	$4.61 Mcf	Basin Specific Swaps - San Juan
2014	5	Bcf	$3.81 Mcf	Basin Specific Swaps - Permian
2015	23	Bcf	$4.13 Mcf	Basin Specific Swaps - San Juan
2015	6	Bcf	$4.20 Mcf	Basin Specific Swaps - Permian
Natural Gas Basis Differential
2014	3.1	Bcf	$(0.09) Mcf	San Juan Basis Swaps
2014	1.2	Bcf	$(0.17) Mcf	Permian Basis Swaps
*WTS - West Texas Sour/Midland, WTI - West Texas Intermediate/Cushing
**WTI - West Texas Intermediate/Midland, WTI - West Texas Intermediate/Cushing
As of June 30, 2014, the maximum term over which Energen has hedged exposures to the variability of cash flows is through December 31, 2015.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	FAIR VALUE MEASUREMENTS
	Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). In determining fair value, we use various valuation approaches and classify all assets and liabilities based on the lowest level of input that is significant to the fair value measurement. Observable inputs represent market data obtained from independent sources, whereas unobservable inputs reflect our own assumptions about the assumptions other market participants would use in pricing the asset or liability based on the best information available in the circumstances. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and its placement within the fair value hierarchy. The hierarchy is broken down into three levels based on the observability of inputs as follows:
	Level 1 -	Unadjusted quoted prices in active markets for identical assets or liabilities;
	Level 2 -	Pricing inputs other than quoted prices in active markets included within Level 1, which are either directly or indirectly observable through correlation with market data as of the reporting date;
	Level 3 -	Pricing that requires inputs that are both significant and unobservable to the calculation of the fair value measure. The fair value measure represents estimates of the assumptions that market participants would use in pricing the asset or liability. Unobservable inputs are developed based on the best available information and subject to cost-benefit constraints.
	No transfers between fair value hierarchy levels occurred during the three months or six months ended June 30, 2014 or 2013.
	Assets and Liabilities Measured at Fair Value on a Recurring Basis
	Energen classifies the fair value of multiple derivative instruments executed under master netting arrangements as net derivative assets and liabilities. The following fair value hierarchy tables present information about Energen’s assets and liabilities measured at fair value on a recurring basis:
		June 30, 2014
	(in thousands)	Level 2			Level 3			Total
	Assets:
	Derivative instruments	$	(2,992	)	$	3,516		$	524
	Noncurrent derivative instruments	—			623			623
	Total assets	(2,992		)	4,139			1,147
	Liabilities:
	Derivative instruments	(95,999		)	(214		)	(96,213		)
	Noncurrent derivative instruments	(22,987		)	1,282			(21,705		)
	Total liabilities	(118,986		)	1,068			(117,918		)
	Net derivative asset (liability)	$	(121,978	)	$	5,207		$	(116,771	)
		31-Dec-13
	(in thousands)	Level 2			Level 3			Total
	Assets:
	Derivative instruments	$	(1,658	)	$	19,121		$	17,463
	Noncurrent derivative instruments	4,383			1,056			5,439
	Total assets	2,725			20,177			22,902
	Liabilities:
	Derivative instruments	(28,414		)	(1,888		)	(30,302		)
	Total liabilities	(28,414		)	(1,888		)	(30,302		)
	Net derivative asset (liability)	$	(25,689	)	$	18,289		$	(7,400	)
	Derivative Instruments: The fair value of Energen’s derivative commodity instruments is determined using market transactions and other market evidence whenever possible, including market-based inputs to models and broker or dealer quotations. Our OTC derivative contracts trade in less liquid markets with limited pricing information as compared to markets with actively traded, unadjusted quoted prices; accordingly, the determination of fair value is inherently more difficult. OTC derivatives for which we are able to substantiate fair value through directly observable market prices are classified within Level 2 of the fair value hierarchy. These Level 2 fair values consist of swaps priced in reference to NYMEX oil and natural gas prices. OTC derivatives valued using unobservable market prices have been classified within Level 3 of the fair value hierarchy. These Level 3 fair values include basin specific, basis and natural gas liquids swaps. We consider the frequency of pricing and variability in pricing between sources in determining whether a market is considered active. While Energen does not have access to the specific assumptions used in its counterparties’ valuation models, Energen maintains communications with its counterparties and discusses pricing practices. Further, we corroborate the fair value of our transactions by comparison of market-based price sources.
	Energen utilizes a discounted cash flow model in valuing its interest rate derivatives, which are comprised of interest rate swap agreements. The fair value attributable to Energen's interest rate derivative contracts is based on (i) the contracted notional amounts, (ii) active market-quoted London Interbank Offered Rate (LIBOR) yield curves and (iii) the applicable credit-adjusted risk-free rate yield curve.
	At June 30, 2014, Energen had interest rate swap agreements with a notional of $190 million. The interest rate swaps exchange a variable interest rate for a fixed interest rate of 2.6675 percent. The fair value of our interest rate swaps was a $1.4 million and a $1.8 million liability at June 30, 2014 and December 31, 2013, respectively, and are classified as a Level 2 fair value liability. The fair value of our interest rate swaps are recognized on a gross basis in accounts payable on the balance sheets.
	Level 3 Fair Value Instruments: Energen prepared a sensitivity analysis to evaluate the hypothetical effect that changes in the prices used to estimate fair value would have on the fair value of its Level 3 instruments. We estimate that a 10 percent increase or decrease in commodity prices would result in an approximate $23 million change in the fair value of open Level 3 derivative contracts. The resulting impact upon the results of operations would be an approximate $23 million associated with open Level 3 derivative contracts. Liquidity requirements to meet the obligation would not be significantly impacted as gains and losses on the derivative contracts would be similarly offset by physical sales at the spot market price.
	The tables below set forth a summary of changes in the fair value of Energen’s Level 3 derivative commodity instruments as follows:
		Three months ended			Three months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Balance at beginning of period	$	1,378		$	26,459
	Realized gains	785			6,183
	Unrealized gains relating to instruments held at the reporting date*	3,800			23,404
	Settlements during period	(756		)	(4,915		)
	Balance at end of period	$	5,207		$	51,131
		Six months ended			Six months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Balance at beginning of period	$	18,289		$	89,019
	Realized gains (losses)	(2,158		)	32,368
	Unrealized losses relating to instruments held at the reporting date*	(13,111		)	(39,156		)
	Settlements during period	2,187			(31,100		)
	Balance at end of period	$	5,207		$	51,131
	*Includes $5.2 million in mark-to-market gains and $4.2 million in mark-to-market losses for the three months and six months ended June 30, 2014, respectively. Includes $8.5 million and $2.7 million in mark-to-market gains for the three months and six months ended June 30, 2013, respectively.
	The tables below set forth quantitative information about the Energen’s Level 3 fair value measurements of derivative commodity instruments as follows:
	(in thousands, except price data)	Fair Value as of June 30, 2014			Valuation Technique*	Unobservable Input*	Range
	Oil Basis - WTS/WTI
	2014	$	1,119		Discounted Cash Flow	Forward Basis	($5.01) Bbl
	Oil Basis - WTI/WTI
	2014	$	3,072		Discounted Cash Flow	Forward Basis	($5.42 - $5.57) Bbl
	Natural Gas Liquids
	2014	$	91		Discounted Cash Flow	Forward Price	$0.74 - $0.97 Gal
	Natural Gas Basis - San Juan
	2014	$	2,817		Discounted Cash Flow	Forward Basis	($0.03 - $0.07) Mcf
	2015	$	579		Discounted Cash Flow	Forward Basis	($0.11 - $0.12) Mcf
	Natural Gas Basis - Permian
	2014	$	(3,073	)	Discounted Cash Flow	Forward Basis	($0.06 - $0.07) Mcf
	2015	$	602		Discounted Cash Flow	Forward Basis	($0.13) Mcf
*Discounted cash flow represents an income approach in calculating fair value including the referenced unobservable input and a discount reflecting credit quality of the counterparty.
Financial Instruments not Carried at Fair Value
The stated value of cash and cash equivalents, short-term investments, accounts receivable (net of allowance), and short-term debt approximates fair value due to the short maturity of the instruments. The fair value of Energen’s long-term debt, including the current portion, was approximately $1,148.7 million and $1,161.9 million and had a carrying value of $1,124.0 million and $1,154.0 million at June 30, 2014 and December 31, 2013, respectively. The fair value of Alagasco’s fixed-rate long-term debt, including the current portion, was approximately $266.6 million and $258.8 million and had a carrying value of $249.8 million and $249.9 million at June 30, 2014 and December 31, 2013, respectively. The fair values are based on market prices of similar debt issues having the same remaining maturities, redemption terms and credit rating. Short-term debt is classified as Level 1 fair value and long-term debt is classified as Level 2 fair value.

Reconciliation_of_Earnings_Per

Reconciliation of Earnings Per Share (EPS)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Reconciliation of Earnings Per Share (EPS)	'
	RECONCILIATION OF EARNINGS PER SHARE (EPS)
		Three months ended							Three months ended
	(in thousands, except per share amounts)	June 30, 2014							June 30, 2013
		Net				Per Share			Net			Per Share
		Income			Shares	Amount			Income		Shares	Amount
	Basic EPS	$	(7,953	)	72,851	$	(0.11	)	$	83,067	72,167	$	1.15
	Effect of dilutive securities
	Stock options				—						225
	Non-vested restricted stock				—						16
	Performance share awards				—						11
	Diluted EPS	$	(7,953	)	72,851	$	(0.11	)	$	83,067	72,419	$	1.15
	In periods of loss, shares that otherwise would have been included in diluted average common shares outstanding are excluded. Energen had 337,614 of excluded shares for the three months ended June 30, 2014.
		Six months ended							Six months ended
	(in thousands, except per share amounts)	June 30, 2014							June 30, 2013
		Net				Per Share			Net			Per Share
		Income			Shares	Amount			Income		Shares	Amount
	Basic EPS	$	45,363		72,737	$	0.62		$	139,759	72,155	$	1.94
	Effect of dilutive securities
	Stock options				165						164
	Non-vested restricted stock				48						10
	Performance share awards				81						—
	Diluted EPS	$	45,363		73,031	$	0.62		$	139,759	72,329	$	1.93
	Energen had the following shares that were excluded from the computation of diluted EPS, as inclusion would be anti-dilutive:
		Three months ended				Six months ended
		June 30,				June 30,
	(in thousands)	2014		2013		2014		2013
	Stock options	114		316		114		687
	Performance share awards	4		—		68		161

Stock_Compensation

Stock Compensation	6 Months Ended
	Jun. 30, 2014
Share-based Compensation [Abstract]	'
Stock Compensation	'
	STOCK COMPENSATION
	Stock Incentive Plan
	Stock Options: The Stock Incentive Plan provides for the grant of incentive stock options and non-qualified stock options to officers and key employees. Options granted under the Stock Incentive Plan provide for the purchase of Energen common stock at not less than the fair market value on the date the option was granted. The sale or transfer of the shares is limited during certain periods. All outstanding options vest within three years from date of grant and expire 10 years from the grant date. Energen granted 107,868 non-qualified option shares during the first quarter of 2014 with a grant-date fair value of $27.57. During the second quarter of 2014, Energen granted 2,439 non-qualified option shares with a grant-date fair value of $32.22.
	Restricted Stock: Additionally, the Stock Incentive Plan provides for the grant of restricted stock units. In January 2014, Energen awarded 41,664 restricted stock units with a grant-date fair value of $70.68. Energen granted 928 restricted stock units during the second quarter of 2014 with a grant-date fair value of $79.15. These awards have a three year vesting period. Energen also granted 6,312 restricted stock units during the second quarter of 2014 with a grant-date fair value of $78.99 and a two year graded vesting period. These awards were valued based on the quoted market price of Energen’s common stock at the date of grant.
	Performance Share Awards: The Stock Incentive Plan also provides for the grant of performance share awards, with each unit equal to the market value of one share of common stock, to eligible employees based on predetermined Company performance criteria at the end of an award period. The Stock Incentive Plan provides that payment of earned performance share awards be made in the form of Energen common stock. Performance share awards are valued using the Monte Carlo model which uses historical volatility and other variables to estimate the probability of satisfying the market condition of the award. Energen granted 287 performance share awards during the first quarter of 2014 with a two year vesting period and a grant-date fair value of $118.99. Energen also granted 63,842 performance share awards during the first quarter of 2014 with a three year vesting period and a grant-date fair value of $93.13. During the second quarter of 2014, Energen granted 650 performance share awards with a two year vesting period and a grant-date fair value of $137.11. Energen also granted 1,467 performance share awards during the second quarter of 2014 with a three year vesting period and a grant-date fair value of $109.02.
	Stock Appreciation Rights Plan
	The Stock Appreciation Rights Plan provides for the payment of cash incentives measured by the long-term appreciation of Energen common stock. These awards are liability awards which settle in cash and are remeasured each reporting period until settlement and have a three year vesting period. Energen granted 62,749 awards during the first quarter of 2014. These awards had a fair value of $42.54 as of June 30, 2014.
	Petrotech Incentive Plan
	The Petrotech Incentive Plan provides for the grant of stock equivalent units. These awards are liability awards which settle in cash and are remeasured each reporting period until settlement. During the first quarter of 2014, Energen awarded 28,840 Petrotech units with a fair value of $88.55 as of June 30, 2014, none of which included a market condition. Also awarded were 36,920 Petrotech units which included a market condition and had a fair value of $122.39 as of June 30, 2014. These awards have a three year vesting period.
	Stock Repurchase Program
	During the three months and six months ended June 30, 2014, we had non-cash purchases of approximately $43,000 and $0.3 million, respectively, of Energen common stock in conjunction with tax withholdings on our non-qualified deferred compensation plan and other stock compensation. Energen utilized internally generated cash flows in payment of the related tax withholdings.

Employee_Benefit_Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]	'
Employee Benefit Plans	'
	EMPLOYEE BENEFIT PLANS
	Effective April 30, 2014, Energen Corporation separated one of its defined benefit non-contributory pension plans into an Energen and an Alagasco plan reflecting the separation of assets and obligations in accordance with ERISA provisions. Energen and Alagasco remeasured these plans using current assumptions.
	The components of net periodic benefit cost for Energen’s defined benefit non-contributory pension plan and certain nonqualified supplemental pension plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	1,621		$	1,327		$	3,256		$	2,654
	Interest cost	1,404			1,088			2,817			2,176
	Expected long-term return on assets	(1,449		)	(1,323		)	(2,909		)	(2,645		)
	Actuarial loss	1,407			1,823			2,819			3,657
	Prior service cost amortization	57			62			114			123
	Settlement charge	115			—			3,673			144
	Net periodic expense	$	3,155		$	2,977		$	9,770		$	6,109
	Included in discontinued operations for the three months and six months ended June 30, 2014 was $2.6 million and $5.3 million, respectively, of net periodic benefit cost for Alagasco’s two defined benefit non-contributory pension plans and allocated costs from the Energen nonqualified supplemental pension plans. Included in discontinued operations for the three months and six months ended June 30, 2013 was $3.5 million and $7.0 million, respectively, of net periodic benefit cost for Alagasco’s two defined benefit non-contributory pension plans and allocated costs from the Energen nonqualified supplemental pension plans.
	Energen anticipates required contributions of approximately $1.6 million during 2014 to the qualified pension plans. Energen expects sufficient funding credits, as established under Internal Revenue Code Section 430(f), exist to meet the required funding. Additionally, it is not anticipated that the funded status of the qualified pension plans will fall below statutory thresholds requiring accelerated funding or constraints on benefit levels or plan administration. Energen made a discretionary contribution of $1.6 million to the qualified pension plans in January 2014. During 2014, Energen may make discretionary contributions to the qualified pension plans depending on the amount and timing of employee retirements and market conditions. For the three months and six months ended June 30, 2014, Energen made benefit payments aggregating $33,000 and $0.9 million, respectively, to retirees from the non-qualified supplemental retirement plans and expects to make additional benefit payments of approximately $5.2 million through the remainder of 2014. In the second quarter of 2014, Energen incurred settlement charges of $0.7 million for the payment of lump sums from the qualified defined benefit pension plans, of which $0.4 million was expensed and $0.3 million was recognized as a pension asset in regulatory assets at Alagasco. In the first quarter of 2014, Energen incurred settlement charges of $6.9 million for the payment of lump sums from the qualified defined benefit pension plans of which $3.7 million is included in discontinued operations. Also in the first quarter of 2014, Energen incurred a settlement charge of $0.4 million for the payment of lump sums from the non-qualified supplemental retirement plans. In the first quarter of 2013, Energen incurred a settlement charge of $0.5 million for the payment of lump sums from the non-qualified supplemental retirement plans, of which $0.1 million was expensed and $0.4 million was recognized as a pension asset in regulatory assets at Alagasco.
	Also effective April 30, 2014, Energen Corporation separated its postretirement health care and life insurance benefit plans into separate plans established for Energen and Alagasco employees in accordance with ERISA provisions. Energen and Alagasco remeasured these plans using current assumptions.
	The components of net periodic postretirement benefit expense for Energen’s postretirement benefit plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	59		$	112		$	119		$	223
	Interest cost	224			176			450			351
	Expected long-term return on assets	(383		)	(214		)	(770		)	(426		)
	Actuarial loss	(209		)	—			(421		)	—
	Transition amortization	15			63			30			126
	Net periodic (income) expense	$	(294	)	$	137		$	(592	)	$	274
	Included in discontinued operations for the three months and six months ended June 30, 2014 was $0.8 million and $1.6 million, respectively, of net periodic postretirement benefit income for Alagasco’s postretirement benefit plans. Included in discontinued operations for the three months and six months ended June 30, 2013 was $0.2 million and $0.5 million, respectively, of net periodic postretirement benefit expense for Alagasco’s postretirement benefit plans. There are no required contributions to the postretirement benefit plans during 2014.
Alabama Gas Corporation	'
Defined Benefit Plan Disclosure [Line Items]	'
Employee Benefit Plans	'
	EMPLOYEE BENEFIT PLANS
	Effective April 30, 2014, Energen Corporation separated one of its defined benefit non-contributory pension plans into an Energen and an Alagasco plan reflecting the separation of assets and obligations in accordance with ERISA provisions. Energen and Alagasco remeasured these plans using current assumptions.
	The components of net periodic benefit cost for Alagasco’s two defined benefit non-contributory pension plans and allocated costs from the Energen nonqualified supplemental pension plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	1,696		$	2,176		$	3,393		$	4,352
	Interest cost	1,439			1,612			2,878			3,225
	Expected long-term return on assets	(1,679		)	(2,315		)	(3,359		)	(4,632		)
	Actuarial loss	1,110			1,937			2,220			3,878
	Prior service cost amortization	71			72			143			144
	Net periodic expense	$	2,637		$	3,482		$	5,275		$	6,967
	Alagasco anticipates required contributions of approximately $2.9 million during 2014 to the qualified pension plans. Alagasco expects sufficient funding credits, as established under Internal Revenue Code Section 430(f), exist to meet the required funding. Additionally, it is not anticipated that the funded status of the qualified pension plans will fall below statutory thresholds requiring accelerated funding or constraints on benefit levels or plan administration. Alagasco made a discretionary contribution of $1.4 million to the qualified pension plans in January 2014. During 2014, Alagasco may make discretionary contributions to the qualified pension plans depending on the amount and timing of employee retirements and market conditions. In the first quarter of 2014, Alagasco incurred a settlement charge of $10.2 million for the payment of lump sums from the qualified defined benefit pension plans which was recognized as a pension asset in regulatory assets at Alagasco.
	Also effective April 30, 2014, Energen Corporation separated its postretirement health care and life insurance benefit plans into separate plans established for Energen and Alagasco employees in accordance with ERISA provisions. Energen and Alagasco remeasured these plans using current assumptions.
	The components of net periodic postretirement benefit (income) expense for Alagasco’s postretirement benefit plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	132		$	314		$	265		$	629
	Interest cost	614			664			1,227			1,328
	Expected long-term return on assets	(1,172		)	(994		)	(2,343		)	(1,989		)
	Actuarial loss	(388		)	—			(777		)	—
	Transition amortization	17			251			34			502
	Net periodic (income) expense	$	(797	)	$	235		$	(1,594	)	$	470
	There are no required contributions to the postretirement benefit plans during 2014.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Purchase Commitment, Excluding Long-term Commitment [Line Items]	'
Commitments and Contingencies	'
	COMMITMENTS AND CONTINGENCIES
	Commitments and Agreements: Under various agreements for third-party gathering, treatment, transportation or other services, Energen is committed to deliver minimum production volumes or to pay certain costs in the event the minimum quantities are not delivered. These delivery commitments are approximately 6 million barrels of oil equivalent (MMBOE) through September 2017.
	Certain of Alagasco’s long-term contracts associated with the delivery and storage of natural gas include fixed charges of approximately $140 million through September 2024. During the six months ended June 30, 2014 and 2013, Alagasco recognized approximately $23.5 million and $26.0 million, respectively, of long-term commitments through expense and its regulatory accounts in the accompanying financial statements. Alagasco also is committed to purchase minimum quantities of gas at market-related prices or to pay certain costs in the event the minimum quantities are not taken. These purchase commitments are approximately 115 Bcf through August 2020.
	Alagasco purchases gas as an agent for certain of its large commercial and industrial customers. Alagasco has, in certain instances, provided commodity-related guarantees to the counterparties in order to facilitate these agency purchases. Liabilities existing for gas delivered to customers subject to these guarantees are included in the balance sheets. In the event the customer for whom the guarantee was entered fails to take delivery of the gas, Alagasco can sell such gas for the customer, with the customer liable for any resulting loss. Although the substantial majority of purchases under these guarantees are for the customers’ current monthly consumption and are at current market prices, in some instances, the purchases are for an extended term at a fixed price. At June 30, 2014, the fixed price purchases under these guarantees had a maximum term outstanding through December 2014 with an aggregate purchase price of $0.3 million and a market value of $0.3 million.
	Legal Matters: Energen and its affiliates are, from time to time, parties to various pending or threatened legal proceedings and we have accrued a provision for our estimated liability. Certain of these lawsuits include claims for punitive damages in addition to other specified relief. We recognize a liability for contingencies when information available indicates both a loss is probable and the amount of the loss can be reasonably estimated. Based upon information presently available, and in light of available legal and other defenses, contingent liabilities arising from threatened and pending litigation are not considered material in relation to the respective financial positions of Energen and its affiliates. It should be noted, however, that there is uncertainty in the valuation of pending claims and prediction of litigation results.
	On December 17, 2013, an incident occurred at a Housing Authority apartment complex in Birmingham, Alabama which resulted in one fatality, personal injuries and property damage. Alagasco is cooperating with the National Transportation Safety Board which is investigating the incident. Alagasco has been named as a defendant in several lawsuits arising from the incident and additional lawsuits and claims may be filed against Alagasco.
	Energen Resources previously disclosed an adverse judgment relating to the ownership of the Company operated Cadenhead 25-1 Well (the Cadenhead Well) in Ward County, Texas. Upon a Motion to Reconsider, the adverse judgment was vacated by the District Court in Ward County, Texas and a Summary Judgment Order dated July 30, 2013 was entered confirming Energen Resources’ superior title to the Cadenhead Well and its associated oil and gas leases. The Summary Judgment Order has been appealed by the other party.
	Environmental Matters: Various environmental laws and regulations apply to the operations of Energen, Energen Resources and Alagasco. Historically, the cost of environmental compliance has not materially affected our financial position, results of operations or cash flows. New regulations, enforcement policies, claims for damages or other events could result in significant unanticipated costs.
	Under oversight of the Site Remediation Section of the Railroad Commission of Texas, Energen Resources is currently in the process of cleanup and remediation of oil and gas wastes in nine reserve pits in Mitchell County, Texas. We estimate that the cleanup, remediation and related costs will approximate $3.4 million of which $1.9 million has been incurred and $0.5 million has been reserved. Also included is a preliminary estimate of $1 million of exposure for further remediation which may be required by the Railroad Commission and is pending further review by the Company.
	During January 2014, Energen Resources responded to a General Notice and Information Request from the Environmental Protection Agency (EPA) regarding the Reef Environmental Site in Sylacauga, Talladega County, Alabama. The letter identifies Energen Resources as a potentially responsible party (PRP) under The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) for the cleanup of the Site. In 2008, Energen hired a third party to transport approximately 3,000 gallons of non-hazardous wastewater to Reef Environmental for wastewater treatment. Reef Environmental ceased operating its wastewater treatment system in 2010. Due to its one time use of Reef Environmental for a small volume of non-hazardous wastewater, Energen Resources has not accrued a liability for cleanup of the Site.
	Alagasco is in the chain of title of nine former manufactured gas plant sites, four of which it still owns, and five former manufactured gas distribution sites, one of which it still owns. Management expects that, should future remediation of the sites be required, Alagasco’s share of the remediation costs will not materially affect the financial position of Alagasco. During 2011, a removal action was completed at the Huntsville, Alabama manufactured gas plant site pursuant to an Administrative Settlement Agreement and Order on Consent among the EPA, Alagasco and the current site owner.
	In 2012, Alagasco responded to an EPA Request for Information Pursuant to Section 104 of CERCLA relating to the 35th Avenue Superfund Site located in North Birmingham, Jefferson County, Alabama. The Request related to a former site of a manufactured gas distribution facility owned by Alagasco and located in the vicinity of the 35th Avenue Superfund Site. In September 2013, Alagasco received from the EPA a General Notice Letter and Invitation to Conduct a Removal Action at the 35th Avenue Superfund Site. The letter identifies Alagasco as a PRP under CERCLA for the cleanup of the Site or costs the EPA incurs in cleaning up the Site. The EPA also offered the PRP group the opportunity to conduct Phase I of the proposed removal action which involved removal activities at approximately 50 residences that purportedly exceed certain risk levels for contamination. Alagasco has discussed its designation as a PRP further with the EPA, and Alagasco has requested additional information from the EPA regarding its designation as a PRP. Alagasco has also been approached by a law firm regarding entry into an agreement to toll the statute of limitations with potential plaintiffs related to purported damages allegedly incurred by such potential plaintiffs in connection with the 35th Avenue Superfund Site, and is considering whether to enter into such a tolling arrangement. Alagasco has not been provided information at this time that would allow it to determine the extent, if any, of its potential liability with respect to the 35th Avenue Superfund Site and the proposed removal action, and therefore Alagasco has not agreed to undertake the proposed removal activities and no amount has been accrued as of June 30, 2014.
	New Mexico Audits: During the third quarter of 2010, Energen Resources received preliminary findings from the Taxation and Revenue Department (the Department) of the State of New Mexico relating to its audit, conducted on behalf of the Office of Natural Resources Revenue (ONRR), of federal oil and gas leases in New Mexico. The audit covered periods from January 2004 through December 2008 and included a review of the computation and payment of royalties due on minerals removed from specified U.S. federal leases. The ONRR has proposed certain changes in the method of determining allowable deductions of transportation, fuel and processing costs from royalties due under the terms of the related leases.
	As a result of the audit, Energen Resources has been ordered by the ONRR to pay additional royalties on the specified U.S. federal leases in the amount of $142,000 and restructure its accounting for all federal leases in two counties in New Mexico from March 1, 2004, forward. Energen preliminarily estimates that application of the Order to all of the Company’s New Mexico federal leases would result in ONRR claims for up to approximately $23 million of additional royalties plus interest and penalties for the period from March 1, 2004, forward. The preliminary findings and subsequent Order (issued April 25, 2011) are contrary to deductions allowed under previous audits, retroactive in application and inconsistent with the Company’s understanding of industry practice. Energen is vigorously contesting the Order and has requested additional information from the ONRR and the Department to assist the Company in evaluating the ONRR Order and the Department’s findings. Management is unable, at this time, to determine a range of reasonably possible losses as a result of this Order, and no amount has been accrued as of June 30, 2014.
Alabama Gas Corporation	'
Purchase Commitment, Excluding Long-term Commitment [Line Items]	'
Commitments and Contingencies	'
	COMMITMENTS AND CONTINGENCIES
	Commitments and Agreements: Certain of Alagasco’s long-term contracts associated with the delivery and storage of natural gas include fixed charges of approximately $140 million through September 2024. During both the six months ending June 30, 2014 and 2013, Alagasco recognized approximately $23.5 million and $26.0 million, respectively, of long-term commitments through expense and its regulatory accounts in the accompanying financial statements. Alagasco also is committed to purchase minimum quantities of gas at market-related prices or to pay certain costs in the event the minimum quantities are not taken. These purchase commitments are approximately 115 Bcf through August 2020.
	Alagasco purchases gas as an agent for certain of its large commercial and industrial customers. Alagasco has, in certain instances, provided commodity-related guarantees to the counterparties in order to facilitate these agency purchases. Liabilities existing for gas delivered to customers subject to these guarantees are included in the balance sheets. In the event the customer for whom the guarantee was entered fails to take delivery of the gas, Alagasco can sell such gas for the customer, with the customer liable for any resulting loss. Although the substantial majority of purchases under these guarantees are for the customers’ current monthly consumption and are at current market prices, in some instances, the purchases are for an extended term at a fixed price. At June 30, 2014, the fixed price purchases under these guarantees had a maximum term outstanding through December 2014 with an aggregate purchase price of $0.3 million with a market value of $0.3 million.
	Legal Matters: Alagasco is, from time to time, a party to various pending or threatened legal proceedings and has accrued a provision for its estimated liability. Certain of these lawsuits include claims for punitive damages in addition to other specified relief. Alagasco recognizes its liability for contingencies when information available indicates both a loss is probable and the amount of the loss can be reasonably estimated. Based upon information presently available, and in light of available legal and other defenses, contingent liabilities arising from threatened and pending litigation are not considered material in relation to the financial position of Alagasco. It should be noted, however, that there is uncertainty in the valuation of pending claims and prediction of litigation results.
	On December 17, 2013, an incident occurred at a Housing Authority apartment complex in Birmingham, Alabama which resulted in one fatality, personal injuries and property damage. Alagasco is cooperating with the National Transportation Safety Board which is investigating the incident. Alagasco has been named as a defendant in several lawsuits arising from the incident and additional lawsuits and claims may be filed against Alagasco.
	Environmental Matters: Various environmental laws and regulations apply to the operations of Alagasco. Historically, the cost of environmental compliance has not materially affected Alagasco’s financial position, results of operations or cash flows. New regulations, enforcement policies, claims for damages or other events could result in significant unanticipated costs.
	Alagasco is in the chain of title of nine former manufactured gas plant sites, four of which it still owns, and five former manufactured gas distribution sites, one of which it still owns. Management expects that, should future remediation of the sites be required, Alagasco’s share of the remediation costs will not materially affect the financial position of Alagasco. During 2011, a removal action was completed at the Huntsville, Alabama manufactured gas plant site pursuant to an Administrative Settlement Agreement and Order on Consent among the EPA, Alagasco and the current site owner.
	In 2012, Alagasco responded to an EPA Request for Information Pursuant to Section 104 of CERCLA relating to the 35th Avenue Superfund Site located in North Birmingham, Jefferson County, Alabama. The Request related to a former site of a manufactured gas distribution facility owned by Alagasco and located in the vicinity of the 35th Avenue Superfund Site. In September 2013, Alagasco received from the EPA a General Notice Letter and Invitation to Conduct a Removal Action at the 35th Avenue Superfund Site. The letter identifies Alagasco as a PRP under CERCLA for the cleanup of the Site or costs the EPA incurs in cleaning up the Site. The EPA also offered the PRP group the opportunity to conduct Phase I of the proposed removal action which involved removal activities at approximately 50 residences that purportedly exceed certain risk levels for contamination. Alagasco has discussed its designation as a PRP further with the EPA, and Alagasco has requested additional information from the EPA regarding its designation as a PRP. Alagasco has also been approached by a law firm regarding entry into an agreement to toll the statute of limitations with potential plaintiffs related to purported damages allegedly incurred by such potential plaintiffs in connection with the 35th Avenue Superfund Site, and is considering whether to enter into such a tolling arrangement. Alagasco has not been provided information at this time that would allow it to determine the extent, if any, of its potential liability with respect to the 35th Avenue Superfund Site and the proposed removal action, and therefore Alagasco has not agreed to undertake the proposed removal activities and no amount has been accrued as of June 30, 2014.

LongTerm_Debt_and_Notes_Payabl

Long-Term Debt and Notes Payable	6 Months Ended
	Jun. 30, 2014
Debt Instrument [Line Items]	'
Long-Term Debt and Notes Payable	'
	LONG-TERM DEBT AND NOTES PAYABLE
	Long-term debt consisted of the following:
	(in thousands)	June 30, 2014			December 31, 2013
	Energen:
	7.40% Medium-term Notes, Series A, due July 24, 2017	$	2,000		$	2,000
	7.36% Medium-term Notes, Series A, due July 24, 2017	15,000			15,000
	7.23% Medium-term Notes, Series A, due July 28, 2017	2,000			2,000
	7.32% Medium-term Notes, Series A, due July 28, 2022	20,000			20,000
	7.60% Medium-term Notes, Series A, due July 26, 2027	5,000			5,000
	7.35% Medium-term Notes, Series A, due July 28, 2027	10,000			10,000
	7.125% Medium-term Notes, Series B, due February 15, 2028	100,000			100,000
	4.625% Notes, due September 1, 2021	400,000			400,000
	Senior Term Loans, (floating rate interest LIBOR plus 1.625%; 1.775% at June 30, 2014), due September 30, 2014 to December 17, 2017	570,000			600,000
		1,124,000			1,154,000
	Less amounts due within one year	570,000			60,000
	Less unamortized debt discount	448			459
	Total Energen	$	553,552		$	1,093,541
	Alagasco:
	5.368% Notes, due December 1, 2015	$	80,000		$	80,000
	5.20% Notes, due January 15, 2020	40,000			40,000
	3.86% Notes, due December 21, 2021	50,000			50,000
	5.70% Notes, due January 15, 2035	34,830			34,923
	5.90% Notes, due January 15, 2037	45,000			45,000
		249,830			249,923
	Less amounts due within one year	50,000			—
	Total Alagasco (included in liabilities related to assets held for sale)	$	199,830		$	249,923
	The aggregate maturities of Energen’s long-term debt outstanding at June 30, 2014 are as follows:
	(in thousands)
	Remaining 2014	2015	2016	2017	2018	2019 and thereafter
	$570,000	—	—	$19,000	—	$535,000
	In December 2013, Energen issued $600 million in Senior Term Loans (Senior Term Loans) with a floating interest rate due March 31, 2014 through December 17, 2017. In conjunction with the pending sale of Alagasco, the Senior Term Loans will be repaid during 2014. In addition, Alagasco’s 3.86 percent Notes, due December 21, 2021 may be required to be repaid upon the sale of Alagasco as specified under certain covenants.
	The long-term debt and short-term debt agreements of Energen and Alagasco contain financial and nonfinancial covenants including routine matters such as timely payment of principal and interest, maintenance of corporate existence and restrictions on liens. Although none of the agreements have covenants or events of default based on credit ratings, the interest rates applicable to the Senior Term Loans and the Energen and Alagasco syndicated credit facilities discussed below may adjust based on credit rating changes. All of Energen’s and Alagasco’s debt is unsecured.
	Under Energen’s Indenture dated September 1, 1996 with The Bank of New York as Trustee, a cross default provision provides that any debt default of more than $10 million by Energen, Energen Resources or Alagasco will constitute an event of default by Energen. Under Alagasco’s Indenture dated November 1, 1993 with The Bank of New York as Trustee, a cross default provision provides that any debt default by Alagasco of more than $10 million will constitute an event of default by Alagasco. Neither Indenture includes a restriction on the payment of dividends.
	Credit Facilities: On October 30, 2012, Energen and Alagasco entered into $1.25 billion and $100 million, respectively, five-year syndicated unsecured credit facilities (syndicated credit facilities) with domestic and foreign lenders. Energen’s obligations under the $1.25 billion syndicated credit facility are unconditionally guaranteed by Energen Resources. The financial covenants of the Energen credit facility limit Energen to a maximum consolidated debt to capitalization ratio of no more than 65 percent as of the end of any fiscal quarter. Energen may not pay dividends during an event of default or if the payment would result in an event of default.
	Under the Energen credit facility, a cross default provision provides that any debt default of more than $50 million by Energen, Energen Resources or Alagasco will constitute an event of default by Energen. Under the Alagasco credit facility, a cross default provision provides that any debt default by Alagasco of more than $50 million will constitute an event of default by Alagasco.
	Upon an uncured event of default under either of the credit facilities, all amounts owing under the defaulted credit facility, if any, depending on the nature of the event of default will automatically, or may upon notice by the administrative agent or the requisite lenders thereunder, become immediately due and payable and the lenders may terminate their commitments under the defaulted facility. Energen and Alagasco were in compliance with the terms of their respective credit facilities as of June 30, 2014.
	The following is a summary of information relating to Energen’s credit facility:
	(in thousands)	June 30, 2014			December 31, 2013
	Energen notes payable to banks	$	669,000		$	489,000
	Available for borrowings	581,000			761,000
	Total Energen	$	1,250,000		$	1,250,000
	Energen maximum amount outstanding at any month-end	$	669,000		$	901,000
	Energen average daily amount outstanding	$	576,486		$	804,895
	Energen weighted average interest rates based on:
	Average daily amount outstanding	1.42		%	1.38		%
	Amount outstanding at period-end	1.4		%	1.32		%
	Energen’s interest expense was $8.0 million and $15.9 million for the three months and six months ended June 30, 2014, respectively. Interest expense for Energen was $10.2 million and $20.1 million for the three months and six months ended June 30, 2013, respectively. For the three months and six months ended June 30, 2014, Energen’s total interest expense included capitalized interest of $37,000. Energen’s total interest expense for the three months and six months ended June 30, 2013 included capitalized interest expense of $34,000 and $0.2 million. At June 30, 2014, Energen paid commitment fees on the unused portion of available credit facilities of 25 basis points per annum. See Note 1, Organization and Basis of Presentation, for further information regarding interest on debt required to be extinguished, associated with the pending sale of Alagasco, which was classified to discontinued operations.
Alabama Gas Corporation	'
Debt Instrument [Line Items]	'
Long-Term Debt and Notes Payable	'
	LONG-TERM DEBT AND NOTES PAYABLE
	Long-term debt consisted of the following:
	(in thousands)	June 30, 2014			December 31, 2013
	5.368% Notes, due December 1, 2015	$	80,000		$	80,000
	5.20% Notes, due January 15, 2020	40,000			40,000
	3.86% Notes, due December 21, 2021	50,000			50,000
	5.70% Notes, due January 15, 2035	34,830			34,923
	5.90% Notes, due January 15, 2037	45,000			45,000
		249,830			249,923
	Less amounts due within one year	50,000			—
	Total	$	199,830		$	249,923
	The aggregate maturities of Alagasco’s long-term debt outstanding at June 30, 2014 are as follows:
	(in thousands)
	Remaining 2014	2015	2016	2017	2018	2019 and thereafter
	$50,000	$80,000	—	—	—	$119,830
	Alagasco’s 3.86 percent Notes due December 21, 2021 may be required to be repaid upon the sale of Alagasco as specified under certain covenants.
	The long-term debt and short-term debt agreements of Alagasco contain financial and nonfinancial covenants including routine matters such as timely payment of principal and interest, maintenance of corporate existence and restrictions on liens. Although none of the agreements have covenants or events of default based on credit ratings, the interest rates applicable to the Alagasco syndicated credit facility discussed below may adjust based on credit rating changes. All of Alagasco’s debt is unsecured.
	Under Alagasco’s Indenture dated November 1, 1993 with The Bank of New York as Trustee, a cross default provision provides that any debt default by Alagasco of more than $10 million will constitute an event of default by Alagasco. The Indenture does not include a restriction on the payment of dividends.
	Alagasco Credit Facility: On October 30, 2012, Alagasco entered into a $100 million five-year syndicated unsecured credit facility (syndicated credit facility) with domestic and foreign lenders. Borrowings under the credit facility are subject to the execution of individual note agreements each with maturity dates of less than one year. Accordingly, outstanding amounts due under the credit facility are classified as short term obligations in the accompanying financial statements. Alagasco has been authorized by the APSC to borrow up to $200 million at any one time under the short-term credit facility.
	The financial covenants of the Alagasco credit facility limit Alagasco to a maximum consolidated debt to capitalization ratio of no more than 65 percent as of the end of any fiscal quarter. Alagasco may not pay dividends during an event of default or if the payment would result in an event of default. Also under the credit facility, a cross default provision provides that any debt default by Alagasco of more than $50 million will constitute an event of default by Alagasco.
	Upon an uncured event of default under the credit facility, all amounts owing under the defaulted credit facility, if any, depending on the nature of the event of default will automatically, or may upon notice by the administrative agent or the requisite lenders thereunder, become immediately due and payable and the lenders may terminate their commitments under the defaulted facility. Alagasco was in compliance with the terms of its credit facility as of June 30, 2014.
	The following is a summary of information relating to the credit facility:
	(in thousands)	June 30, 2014			December 31, 2013
	Notes payable to banks	$	—		$	50,000
	Available for borrowings	100,000			50,000
	Total	$	100,000		$	100,000
	Alagasco maximum amount outstanding at any month-end	$	55,000		$	75,000
	Alagasco average daily amount outstanding	$	17,956		$	35,027
	Alagasco weighted average interest rates based on:
	Average daily amount outstanding	1.28		%	1.12		%
	Amount outstanding at period-end	—		%	1.26		%
	Total interest expense for Alagasco was $3.7 million and $7.7 million for the three months and six months ended June 30, 2014, respectively. Alagasco’s total interest expense was $3.8 million and $7.9 million for the three months and six months ended June 30, 2013, respectively. At June 30, 2014, Alagasco paid commitment fees on the unused portion of available credit facilities of 15 basis points per annum.

Exploratory_Costs

Exploratory Costs	6 Months Ended
	Jun. 30, 2014
Extractive Industries [Abstract]	'
Exploratory Costs	'
	EXPLORATORY COSTS
	Energen capitalizes exploratory drilling costs until a determination is made that the well or project has either found proved reserves or is impaired. After an exploratory well has been drilled and found oil and natural gas reserves, a determination may be pending as to whether the oil and natural gas quantities can be classified as proved. In those circumstances, Energen continues to capitalize the drilling costs pending the determination of proved status if (i) the well has found a sufficient quantity of reserves to justify its completion as a producing well and (ii) Energen is making sufficient progress assessing the reserves and the economic and operating viability of the project. Capitalized exploratory drilling costs are presented in unproved properties in the balance sheets. If the exploratory well is determined to be impaired, the impaired costs are charged to exploration expense. Other exploration costs, including geological and geophysical costs, are expensed as incurred.
	The following table sets forth capitalized exploratory well costs and includes additions pending determination of proved reserves, reclassifications to proved reserves and costs charged to expense:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Capitalized exploratory well costs at beginning of period	$	109,968		$	106,175		$	57,600		$	79,791
	Additions pending determination of proved reserves	200,347			123,719			365,189			219,580
	Reclassifications due to determination of proved reserves	(142,666		)	(157,722		)	(255,140		)	(227,199		)
	Exploratory well costs charged to expense	(1,191		)	—			(1,191		)	—
	Capitalized exploratory well costs at end of period	$	166,458		$	72,172		$	166,458		$	72,172
	The following table sets forth capitalized exploratory wells costs and includes amounts capitalized for a period greater than one year:
		Six months ended			Six months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Exploratory wells in progress	$	35,753		$	25,728
	Capitalized exploratory well costs capitalized for a period of one year or less	129,477			45,245
	Capitalized exploratory well costs for a period greater than one year	1,228			1,199
	Total capitalized exploratory well costs	$	166,458		$	72,172
	At June 30, 2014, Energen had 56 gross exploratory wells either drilling or waiting on results from completion and testing. These wells are located primarily in the Permian Basin. Energen has one gross well capitalized greater than a year which is pending results from completion and testing. This well is currently waiting on facilities.

Financial_Instruments

Financial Instruments (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'
Financial Instruments	'
	FINANCIAL INSTRUMENTS
	The stated value of cash, accounts receivable (net of allowance) and short-term debt approximates fair value due to the short maturity of the instruments. The fair value of Alagasco’s fixed-rate long-term debt, including the current portion, was approximately $266.6 million and $258.8 million and had a carrying value of $249.8 million and $249.9 million at June 30, 2014 and December 31, 2013, respectively. The fair values are based on market prices of similar debt issues having the same remaining maturities, redemption terms and credit rating. Short-term debt is classified as Level 1 fair value and long-term debt is classified as Level 2 fair value.
	Finance Receivables: Alagasco finances third-party contractor sales of merchandise including gas furnaces and appliances. At June 30, 2014 and December 31, 2013, Alagasco’s finance receivable totaled $10.6 million and $10.8 million, respectively. These finance receivables currently have an average balance of approximately $3,000 with terms of up to 84 months. Financing is available only to qualified customers who meet creditworthiness thresholds for customer payment history and external agency credit reports. Alagasco relies upon ongoing payments as the primary indicator of credit quality during the term of each contract. The allowance for credit losses is recognized using an estimate of write-off percentages based on historical experience applied to an aging of the finance receivable balance. Delinquent accounts are evaluated on a case-by-case basis and, absent evidence of debt repayment after 90 days, are due in full and assigned to a third-party collection agency. The remaining finance receivable is written off approximately 12 months after being assigned to a third-party collection agency. Alagasco had finance receivables past due 90 days or more of $0.3 million and $0.4 million as of June 30, 2014 and December 31, 2013, respectively.
	The following table sets forth a summary of changes in the allowance for credit losses as follows:
	(in thousands)
	Allowance for credit losses as of December 31, 2013	$	423
	Provision	(118		)
	Allowance for credit losses as of June 30, 2014	$	305

Regulatory_Assets_and_Liabilit

Regulatory Assets and Liabilities (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Regulatory Assets and Liabilities [Line Items]	'
Regulatory Assets and Liabilities	'
	REGULATORY ASSETS AND LIABILITIES
	The following table details regulatory assets and liabilities on the balance sheets:
	(in thousands)	June 30, 2014				31-Dec-13
		Current		Noncurrent		Current		Noncurrent
	Regulatory assets:
	Pension assets	$	1,284	$	65,627	$	325	$	58,243
	Accretion and depreciation of asset retirement obligations	—		18,825		—		18,046
	Rate recovery of asset removal costs, net	—		3,405		—		4,601
	Enhanced stability reserve	—		4,000		—		4,000
	Gas supply adjustment	—		—		2,406		—
	RSE adjustment	1,032		—		25		—
	Total regulatory assets	$	2,316	$	91,857	$	2,756	$	84,890
	Regulatory liabilities:
	RSE adjustment	$	18,578	$	—	$	4,690	$	—
	Unbilled service margin	6,445		—		28,504		—
	Postretirement liabilities	—		26,948		—		26,197
	Gas supply adjustment	25,985		—		—		—
	Refundable negative salvage	13,360		26,760		15,779		39,663
	Asset retirement obligation	—		28,152		—		27,528
	Other	33		720		33		737
	Total regulatory liabilities	$	64,401	$	82,580	$	49,006	$	94,125

Asset_Retirement_Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2014
Asset Retirement Obligations [Line Items]	'
Asset Retirement Obligations	'
	ASSET RETIREMENT OBLIGATIONS
	Energen’s asset retirement obligations (ARO) primarily relate to the future plugging, abandonment and reclamation of wells and facilities. We recognize a liability for the fair value of the ARO in the periods incurred. The ARO fair value liability is determined by calculating the present value of the estimated future cash outflows we expect to incur to plug, abandon and reclaim our producing properties at the end of their productive lives, and is recognized on a discounted basis incorporating an estimate of performance risk specific to Energen. Subsequent to initial measurement, liabilities are accreted to their present value and capitalized costs are depreciated over the estimated useful lives of the related assets. Upon settlement of the liability, Energen may recognize a gain or loss for differences between estimated and actual settlement costs.
	The following table reflects the components of the change in Energen’s ARO balance for the six months ended June 30, 2014:
	(in thousands)
	Balance as of December 31, 2013	$	108,533
	Liabilities incurred	1,504
	Liabilities settled	(676		)
	Accretion expense	3,726
	Balance as of June 30, 2014	$	113,087
Alabama Gas Corporation	'
Asset Retirement Obligations [Line Items]	'
Asset Retirement Obligations	'
	ASSET RETIREMENT OBLIGATIONS
	Alagasco recognizes a liability for the fair value of asset retirement obligations (ARO) in the periods incurred. Subsequent to initial measurement, liabilities are accreted to their present value and capitalized costs are depreciated over the estimated useful lives of the related assets. The ARO fair value liability is recognized on a discounted basis incorporating an estimate of performance risk specific to Alagasco.
	Alagasco recognizes conditional obligations if such obligations can be reasonably estimated and a legal requirement to perform an asset retirement activity exists. Alagasco accrues removal costs on certain gas distribution assets over the useful lives of its property, plant and equipment through depreciation expense in accordance with rates approved by the APSC. Alagasco recorded a conditional asset retirement obligation, on a discounted basis, of $28.2 million and $27.5 million to purge and cap its gas pipelines upon abandonment and to remediate other related obligations, as a regulatory liability as of June 30, 2014 and December 31, 2013, respectively. Regulatory assets for rate recovery of accumulated asset removal costs of $3.4 million and $4.6 million as of June 30, 2014 and December 31, 2013, are included as regulatory assets in noncurrent assets on the balance sheets. The costs associated with asset retirement obligations are either currently being recovered in rates or are probable of recovery in future rates.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income (Loss)	'
	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	The following table provides changes in the components of accumulated other comprehensive income (loss), net of the related income tax effects.
	(in thousands)	Cash Flow Hedges			Pension and Postretirement Plans			Total
	Balance as of December 31, 2013	$	12,178		$	(32,245	)	$	(20,067	)
	Other comprehensive income (loss) before reclassifications	(287		)	(2,136		)	(2,423		)
	Amounts reclassified from accumulated other comprehensive income (loss)	(4,748		)	6,739			1,991
	Change in accumulated other comprehensive income (loss)	(5,035		)	4,603			(432		)
	Balance as of June 30, 2014	$	7,143		$	(27,642	)	$	(20,499	)
	The following table provides details of the reclassifications out of accumulated other comprehensive income (loss).
		Three months ended			Three months ended
		30-Jun-14			30-Jun-13
	(in thousands)	Amounts Reclassified						Line Item Where Presented
	Gains (losses) on cash flow hedges:
	Commodity contracts	$	5,735		$	4,503		Gain (loss) on derivative instruments, net
	Interest rate swap	(1,588		)	(426		)	Interest expense
	Total cash flow hedges	4,147			4,077
	Income tax expense	(1,623		)	(1,562		)
	Net of tax	2,524			2,515
	Pension and postretirement plans:
	Transition obligation	(9		)	(74		)	General and administrative
	Prior service cost	(74		)	(78		)	General and administrative
	Actuarial losses	(1,289		)	(2,097		)	General and administrative
	Actuarial losses on settlement charges	(360		)	—			General and administrative
	Total pension and postretirement plans	(1,732		)	(2,249		)
	Income tax expense	606			788
	Net of tax	(1,126		)	(1,461		)
	Total reclassifications for the period	$	1,398		$	1,054
		Six months ended			Six months ended
		30-Jun-14			30-Jun-13
	(in thousands)	Amounts Reclassified						Line Item Where Presented
	Gains (losses) on cash flow hedges:
	Commodity contracts	$	9,789		$	21,792		Gain (loss) on derivative instruments, net
	Interest rate swap	(2,033		)	(836		)	Interest expense
	Total cash flow hedges	7,756			20,956
	Income tax expense	(3,008		)	(7,989		)
	Net of tax	4,748			12,967
	Pension and postretirement plans:
	Transition obligation	(19		)	(147		)	General and administrative
	Prior service cost	(148		)	(157		)	General and administrative
	Actuarial losses*	(2,580		)	(4,350		)	General and administrative
	Actuarial losses on settlement charges	(7,622		)	—			General and administrative
	Actuarial losses on settlement charges*	—			(375		)	Assets held for sale as of June 30, 2014 with prior period comparable
	Total pension and postretirement plans	(10,369		)	(5,029		)
	Income tax expense	3,630			1,761
	Net of tax	(6,739		)	(3,268		)
	Total reclassifications for the period	$	(1,991	)	$	9,699
	* In the first quarter of 2013, Energen incurred a settlement charge of $0.5 million for the payment of lump sums from the nonqualified supplemental retirement plans, of which $0.1 million was recognized in actuarial losses above and $0.4 million was recognized as a regulatory asset at Alagasco and reported in actuarial losses on settlement charges above.

Discontinued_Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	DISCONTINUED OPERATIONS
	In April 2014, Energen signed a stock purchase agreement to sell Alagasco to Laclede for $1.6 billion, subject to closing adjustments, which includes an estimated $1.28 billion in cash and the assumption of $320 million in debt. This sale is expected to close during 2014. Energen plans to use cash proceeds from the sale to reduce long-term and short-term indebtedness. During the second quarter of 2014, Energen classified Alagasco as held for sale with prior period comparable and reflected the associated operating results in discontinued operations. Our results of operations for the three months and six months ended June 30, 2014 and 2013 and our financial position as of June 30, 2014 and December 31, 2013 presented in our unaudited consolidated financial statements and these notes reflect Alagasco as discontinued operations.
	In March 2014, Energen completed the sale of its North Louisiana/East Texas natural gas and oil properties for $30.3 million (subject to closing adjustments). The sale had an effective date of December 1, 2013, and the proceeds from the sale were used to repay short-term obligations. During the third quarter of 2013, Energen classified these natural gas and oil properties as held for sale and reflected the associated operating results in discontinued operations. Energen recognized a non-cash impairment writedown on these properties in the first quarter of 2014 of $1.7 million pre-tax to adjust the carrying amount of these properties to their fair value based on an estimate of the selling price of the properties. This non-cash impairment writedown is reflected in loss on disposal of discontinued operations in the six months ended June 30, 2014. Energen also recognized non-cash impairment writedowns on these properties in the third and fourth quarters of 2013 of $24.6 million pre-tax and $5.2 million pre-tax, respectively. Significant assumptions in valuing the proved reserves included the reserve quantities, anticipated operating costs, anticipated production taxes, future expected natural gas prices and basis differentials, anticipated production declines, and a discount rate of 10 percent commensurate with the risk of the underlying cash flow estimates. The impairment writedowns are classified as Level 3 fair value. At December 31, 2013, proved reserves associated with Energen’s North Louisiana/East Texas properties totaled 23 Bcf of natural gas and 91 MBbl of oil.
	In October 2013, Energen completed the sale of its Black Warrior Basin coalbed methane properties in Alabama for $160 million (subject to closing adjustments). Energen recorded a pre-tax gain on the sale of approximately $35 million in the fourth quarter of 2013 which was reflected in gain on disposal of discontinued operations in the year ended December 31, 2013. The sale had an effective date of July 1, 2013, and the proceeds from the sale were used to repay short-term obligations. The property was classified as held for sale and reflected in discontinued operations during the third quarter of 2013. At December 31, 2012, proved reserves associated with Energen’s Black Warrior Basin properties totaled 97 Bcf of natural gas.
	The following tables detail held for sale properties by major classes of assets and liabilities:
	(in thousands)				June 30, 2014
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	11,807		$	—		$	—		$	11,807
	Accounts receivable*	50,285			—			—			50,285
	Inventories	39,950			—			—			39,950
	Utility plant	1,517,534			—			—			1,517,534
	Less accumulated depreciation	(624,704		)	—			—			(624,704		)
	Other property, net	40			—			—			40
	Other current assets*	16,462			—			—			16,462
	Other long-term assets	142,672			—			—			142,672
	Total assets held for sale	1,154,046			—			—			1,154,046
	Accounts payable	(38,646		)	(2,172		)	(1,856		)	(42,674		)
	Royalty payable	—			—			(1,284		)	(1,284		)
	Accrued taxes*	(29,337		)	—			—			(29,337		)
	Long-term debt due within one year	(50,000		)	—			—			(50,000		)
	Other current liabilities	(108,633		)	—			(2		)	(108,635		)
	Other long-term liabilities	(335,369		)	—			(2		)	(335,371		)
	Long-term debt	(199,830		)	—			—			(199,830		)
	Total liabilities held for sale	(761,815		)	(2,172		)	(3,144		)	(767,131		)
	Total net assets held for sale	$	392,231		$	(2,172	)	$	(3,144	)	$	386,915
	(in thousands)				31-Dec-13
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	3,032		$	—		$	—		$	3,032
	Accounts receivable*	103,748			2,829			1,272			107,849
	Inventories	41,200			—			68			41,268
	Oil and gas properties	—			—			348,379			348,379
	Less accumulated depreciation, depletion and amortization	—						(301,609		)	(301,609		)
	Utility plant	1,491,433			—			—			1,491,433
	Less accumulated depreciation	(605,924		)	—			—			(605,924		)
	Other property, net	41			—			165			206
	Other current assets*	29,458			—			—			29,458
	Other long-term assets	128,780			—			—			128,780
	Total assets held for sale	1,191,768			2,829			48,275			1,242,872
	Accounts payable	(48,653		)	(1,732		)	(11		)	(50,396		)
	Royalty payable	—			(550		)	(869		)	(1,419		)
	Accrued taxes	(28,027		)	—			—			(28,027		)
	Notes payable to banks	(50,000		)	—			—			(50,000		)
	Other current liabilities*	(105,013		)	(379		)	(21		)	(105,413		)
	Other long-term liabilities	(331,409		)	—			(14,983		)	(346,392		)
	Long-term debt	(249,923		)	—			—			(249,923		)
	Total liabilities held for sale	(813,025		)	(2,661		)	(15,884		)	(831,570		)
	Total net assets held for sale	$	378,743		$	168		$	32,391		$	411,302
	*At June 30, 2014, Alagasco’s accounts receivable, other current assets and accrued taxes included consolidating adjustments of $13.2 million to adjust for affiliated companies receivables and a $7.9 million reclassification from accrued taxes to other current assets. At December 31, 2013, Alagasco’s accounts receivable included a consolidating adjustment of $4.7 million to adjust for affiliated companies receivables. Certain other current assets and other current liabilities at Alagasco of $1.6 million and $0.5 million, respectively, were reclassified to continuing operations at Energen.
	We recognized interest on debt required to be extinguished in connection with the pending sale of Alagasco as discontinued operations. During 2014, we will enter into a new credit facility. We expect this credit facility to be secured by assets of Energen and its subsidiaries. The interest associated with the five-year syndicated unsecured credit facilities was also classified as discontinued operations. See Note 1, Organization and Basis of Presentation, for further information regarding adjustments associated with the pending sale of Alagasco.
	Gains and losses on the sale of certain oil and gas properties as well as any impairments of properties held for sale are reported as discontinued operations, with income or loss from operations of the associated assets reported as income or loss from discontinued operations. The results of operations for certain held for sale assets were reclassified and reported as discontinued operations for all prior periods presented. Energen may, in the ordinary course of business, be involved in the sale of developed or undeveloped properties. All assets held for sale are reported at the lower of the carrying amount or fair value.
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands, except per share data)	2014			2013			2014			2013
	Natural gas distribution revenues	$	93,873		$	104,514		$	357,774		$	342,199
	Oil and natural gas revenues	390			18,562			5,211			37,225
	Total revenues	$	94,263		$	123,076		$	362,985		$	379,424
	Pretax income (loss) from discontinued operations	$	(7,797	)	$	967		$	54,519		$	78,775
	Income tax expense (benefit)	(2,998		)	322			20,599			29,857
	Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	33,920		$	48,918
	Loss on disposal of discontinued operations	$	—		$	—		$	(1,667	)	$	—
	Income tax benefit	—			—			(617		)	—
	Loss on Disposal of Discontinued Operations	$	—		$	—		$	(1,050	)	$	—
	Total Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	32,870		$	48,918
Diluted Earnings Per Average Common Share
Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.67
Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.67
Basic Earnings Per Average Common Share
Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.68
Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.68

Disposition_of_Properties

Disposition of Properties (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'
Dispositions of Properties	'
	DISPOSITION OF PROPERTIES
	In August 2013, Alagasco recorded a pre-tax gain of $10.9 million related to the sale of its Metro Operations Center which is located in Birmingham, Alabama, and has been in service since the 1940’s. Alagasco received approximately $13.8 million pre-tax in cash from the sale of this property. During the third quarter of 2013, the gain on the sale was recognized in other income and a related reduction in revenues was recognized to defer the gain as a regulatory liability pending review by the APSC. In conjunction with the receipt of the rate order from the APSC on December 20, 2013, Alagasco recognized the deferred revenues from this sale in the fourth quarter of 2013. Effective upon the sale of the Metro Operations Center, Alagasco leased the facility from the purchaser for a period of approximately 20 months.
	In the second quarter of 2014, Alagasco sold property in Tuscaloosa resulting in a gain of approximately $0.7 million pre-tax, which was recorded in other income.

Recently_Issued_Accounting_Sta

Recently Issued Accounting Standards	6 Months Ended
	Jun. 30, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
Recently Issued Accounting Standards	'
	RECENTLY ISSUED ACCOUNTING STANDARDS
	In April 2014, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This update defines a discontinued operation as a disposal of a component or a group of components that is disposed of or is classified as held for sale and represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The amendment is effective for all annual periods beginning on or after December 15, 2014, and interim periods within those annual periods. Energen is currently evaluating the impact of this ASU.
Alabama Gas Corporation	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
Recently Issued Accounting Standards	'
	RECENTLY ISSUED ACCOUNTING STANDARDS
	In April 2014, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This update defines a discontinued operation as a disposal of a component or a group of components that is disposed of or is classified as held for sale and represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The amendment is effective for all annual periods beginning on or after December 15, 2014, and interim periods within those annual periods. Alagasco is currently evaluating the impact of this ASU.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation Organization and Basis of presentation (Policies) (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Basis of Accounting, Policy	'
	The accompanying unaudited financial statements and notes should be read in conjunction with the financial statements and notes thereto for the years ended December 31, 2013, 2012 and 2011, included in the 2013 Annual Report of Energen Corporation (Energen) and Alabama Gas Corporation on Form 10-K and have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the disclosures required for complete financial statements. Alagasco’s natural gas distribution business is seasonal in character and influenced by weather conditions, and therefore, the results of operations for interim periods are not necessarily indicative of the results that may be expected for the year. All adjustments to the unaudited financial statements that are, in the opinion of management, necessary for a fair statement of the results for the interim periods have been recorded. Such adjustments consist of normal recurring items.

Recently_Issued_Accounting_Sta1

Recently Issued Accounting Standards (Policies)	6 Months Ended
	Jun. 30, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
New Accounting Pronouncements, Policy	'
	RECENTLY ISSUED ACCOUNTING STANDARDS
	In April 2014, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This update defines a discontinued operation as a disposal of a component or a group of components that is disposed of or is classified as held for sale and represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The amendment is effective for all annual periods beginning on or after December 15, 2014, and interim periods within those annual periods. Energen is currently evaluating the impact of this ASU.
Alabama Gas Corporation	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
New Accounting Pronouncements, Policy	'
	In April 2014, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity. This update defines a discontinued operation as a disposal of a component or a group of components that is disposed of or is classified as held for sale and represents a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The amendment is effective for all annual periods beginning on or after December 15, 2014, and interim periods within those annual periods. Alagasco is currently evaluating the impact of this ASU.

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation (Tables)	6 Months Ended
	Jun. 30, 2014
Derivative Instruments, Gain (Loss)	'
	We further reclassified all commodity hedges from oil and natural gas operating revenues to gain (loss) on derivative instruments, net, as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Open non-cash mark-to-market gains (losses) on derivative instruments	$	(59,621	)	$	56,149		$	(93,302	)	$	15,101
	Closed gains (losses) on derivative instruments	$	(25,225	)	$	(905	)	$	(44,935	)	$	21,187
	Gain (loss) on derivative instruments, net	$	(84,846	)	$	55,244		$	(138,237	)	$	36,288
Schedule of Discontinued Operations	'
	he table below provides a detail of these items included in income (loss) from discontinued operations at June 30, 2014:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Alagasco net income (loss)	$	(615	)	$	(704	)	$	42,413		$	46,518
	Depreciation, depletion and amortization	(153		)	(147		)	(305		)	(294		)
	General and administrative	687			1,724			1,627			3,578
	Interest expense	(7,190		)	(3,288		)	(12,977		)	(6,109		)
	Other income	(228		)	(64		)	(347		)	(473		)
	Income tax expense (benefit)	2,603			671			4,538			1,247
	Alagasco income (loss) from discontinued operations	(4,896		)	(1,808		)	34,949			44,467
	Energen income (loss) from discontinued operations	97			2,453			(1,029		)	4,451
	Income (loss) from discontinued operations	$	(4,799	)	$	645		$	33,920		$	48,918
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands, except per share data)	2014			2013			2014			2013
	Natural gas distribution revenues	$	93,873		$	104,514		$	357,774		$	342,199
	Oil and natural gas revenues	390			18,562			5,211			37,225
	Total revenues	$	94,263		$	123,076		$	362,985		$	379,424
	Pretax income (loss) from discontinued operations	$	(7,797	)	$	967		$	54,519		$	78,775
	Income tax expense (benefit)	(2,998		)	322			20,599			29,857
	Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	33,920		$	48,918
	Loss on disposal of discontinued operations	$	—		$	—		$	(1,667	)	$	—
	Income tax benefit	—			—			(617		)	—
	Loss on Disposal of Discontinued Operations	$	—		$	—		$	(1,050	)	$	—
	Total Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	32,870		$	48,918
	Diluted Earnings Per Average Common Share
	Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.67
	Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
	Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.67
	Basic Earnings Per Average Common Share
	Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.68
	Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
	Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.68
	The following tables detail held for sale properties by major classes of assets and liabilities:
	(in thousands)				June 30, 2014
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	11,807		$	—		$	—		$	11,807
	Accounts receivable*	50,285			—			—			50,285
	Inventories	39,950			—			—			39,950
	Utility plant	1,517,534			—			—			1,517,534
	Less accumulated depreciation	(624,704		)	—			—			(624,704		)
	Other property, net	40			—			—			40
	Other current assets*	16,462			—			—			16,462
	Other long-term assets	142,672			—			—			142,672
	Total assets held for sale	1,154,046			—			—			1,154,046
	Accounts payable	(38,646		)	(2,172		)	(1,856		)	(42,674		)
	Royalty payable	—			—			(1,284		)	(1,284		)
	Accrued taxes*	(29,337		)	—			—			(29,337		)
	Long-term debt due within one year	(50,000		)	—			—			(50,000		)
	Other current liabilities	(108,633		)	—			(2		)	(108,635		)
	Other long-term liabilities	(335,369		)	—			(2		)	(335,371		)
	Long-term debt	(199,830		)	—			—			(199,830		)
	Total liabilities held for sale	(761,815		)	(2,172		)	(3,144		)	(767,131		)
	Total net assets held for sale	$	392,231		$	(2,172	)	$	(3,144	)	$	386,915
	(in thousands)				31-Dec-13
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	3,032		$	—		$	—		$	3,032
	Accounts receivable*	103,748			2,829			1,272			107,849
	Inventories	41,200			—			68			41,268
	Oil and gas properties	—			—			348,379			348,379
	Less accumulated depreciation, depletion and amortization	—						(301,609		)	(301,609		)
	Utility plant	1,491,433			—			—			1,491,433
Less accumulated depreciation	(605,924		)	—			—			(605,924		)
Other property, net	41			—			165			206
Other current assets*	29,458			—			—			29,458
Other long-term assets	128,780			—			—			128,780
Total assets held for sale	1,191,768			2,829			48,275			1,242,872
Accounts payable	(48,653		)	(1,732		)	(11		)	(50,396		)
Royalty payable	—			(550		)	(869		)	(1,419		)
Accrued taxes	(28,027		)	—			—			(28,027		)
Notes payable to banks	(50,000		)	—			—			(50,000		)
Other current liabilities*	(105,013		)	(379		)	(21		)	(105,413		)
Other long-term liabilities	(331,409		)	—			(14,983		)	(346,392		)
Long-term debt	(249,923		)	—			—			(249,923		)
Total liabilities held for sale	(813,025		)	(2,661		)	(15,884		)	(831,570		)
Total net assets held for sale	$	378,743		$	168		$	32,391		$	411,302

Derivative_Commodity_Instrumen1

Derivative Commodity Instruments Derivative Commodity Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Derivative Liabilities at Fair Value	'
	The following tables detail the offsetting of derivative assets and liabilities as well as the fair values of derivatives on the balance sheets:
	(in thousands)	30-Jun-14
											Gross Amounts Not Offset in the Balance Sheets
		Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amount Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
	Derivatives not designated as hedging instruments
	Assets
	Derivative instruments	$	14,540		$	(14,016	)	$	524		$	—	$	—	$	524
	Noncurrent derivative instruments	2,076			(1,453		)	623			—		—		623
	Total derivative assets	16,616			(15,469		)	1,147			—		—		1,147
	Liabilities
	Derivative instruments	110,229			(14,016		)	96,213			—		—		96,213
	Noncurrent derivative instruments	23,158			(1,453		)	21,705			—		—		21,705
	Total derivative liabilities	133,387			(15,469		)	117,918			—		—		117,918
	Total derivatives	$	(116,771	)	$	—		$	(116,771	)	$	—	$	—	$	(116,771	)
	he following tables detail the offsetting of derivative assets and liabilities as well as the fair values of derivatives on the balance sheets:
	(in thousands)	30-Jun-14
											Gross Amounts Not Offset in the Balance Sheets
		Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amount Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
	Derivatives not designated as hedging instruments
	Assets
	Derivative instruments	$	14,540		$	(14,016	)	$	524		$	—	$	—	$	524
	Noncurrent derivative instruments	2,076			(1,453		)	623			—		—		623
	Total derivative assets	16,616			(15,469		)	1,147			—		—		1,147
	Liabilities
	Derivative instruments	110,229			(14,016		)	96,213			—		—		96,213
	Noncurrent derivative instruments	23,158			(1,453		)	21,705			—		—		21,705
	Total derivative liabilities	133,387			(15,469		)	117,918			—		—		117,918
	Total derivatives	$	(116,771	)	$	—		$	(116,771	)	$	—	$	—	$	(116,771	)
	(in thousands)	31-Dec-13
											Gross Amounts Not Offset in the Balance Sheets
		Gross Amounts Recognized at Fair Value			Gross Amounts Offset in the Balance Sheets			Net Amount Presented in the Balance Sheets			Financial Instruments		Cash Collateral Received		Net Fair Value Presented in the Balance Sheets
	Derivatives not designated as hedging instruments
	Assets
	Derivative instruments	$	36,223		$	(18,760	)	$	17,463		$	—	$	—	$	17,463
	Noncurrent derivative instruments	7,992			(2,553		)	5,439			—		—		5,439
	Total derivative assets	44,215			(21,313		)	22,902			—		—		22,902
	Liabilities
	Derivative instruments	49,062			(18,760		)	30,302			—		—		30,302
	Noncurrent derivative instruments	2,553			(2,553		)	—			—		—		—
	Total derivative liabilities	51,615			(21,313		)	30,302			—		—		30,302
	Total derivatives	$	(7,400	)	$	—		$	(7,400	)	$	—	$	—	$	(7,400	)
Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location	'
	The following table details the effect of derivative commodity instruments in cash flow hedging relationships on the financial statements:
	(in thousands)	Location on Statements of Income	Three months			Three months
			ended			ended
			30-Jun-14			30-Jun-13
	Net gain recognized in other comprehensive income on derivatives (effective portion), net of tax of $6 and $9,713	—	$	9		$	15,847
	Gain reclassified from accumulated other comprehensive income into income (effective portion)	Gain (loss) on derivative instruments, net	$	5,735		$	3,112
	Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	Gain (loss) on derivative instruments, net	$	—		$	1,392
	(in thousands)	Location on Statements of Income	Six months			Six months
			ended			ended
			30-Jun-14			30-Jun-13
	Net gain (loss) recognized in other comprehensive income on derivatives (effective portion), net of tax of $7 and ($6,712)	—	$	11		$	(10,951	)
	Gain reclassified from accumulated other comprehensive income into income (effective portion)	Gain (loss) on derivative instruments, net	$	9,789		$	20,935
	Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	Gain (loss) on derivative instruments, net	$	—		$	858
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	'
	The following table details the effect of open and closed derivative commodity instruments not designated as hedging instruments on the income statement:
	(in thousands)	Location on Statements of Income	Three months			Three months
			ended			ended
			30-Jun-14			30-Jun-13
	Gain (loss) recognized in income on derivatives	Gain (loss) on derivative instruments, net	$	(90,581	)	$	53,078
	(in thousands)	Location on Statements of Income	Six months			Six months
			ended			ended
			30-Jun-14			30-Jun-13
	Gain (loss) recognized in income on derivatives	Gain (loss) on derivative instruments, net	$	(148,026	)	$	21,577
Schedule of Hedging Transactions	'
	Energen had entered into the following transactions for the remainder of 2014 and subsequent years:
	Production Period	Total Hedged Volumes		Average Contract	Description
				Price
	Oil
	2014	4,958	MBbl	$92.65 Bbl	NYMEX Swaps
	2015	8,280	MBbl	$89.30 Bbl	NYMEX Swaps
	Oil Basis Differential
	2014	600	MBbl	$(3.30) Bbl	WTS/WTI Basis Swaps*
	2014	1,200	MBbl	$(3.08) Bbl	WTI/WTI Basis Swaps**
	Natural Gas Liquids
	2014	35.8	MMgal	$0.93 Gal	Liquids Swaps
	Natural Gas
	2014	5.2	Bcf	$4.56 Mcf	NYMEX Swaps
	2014	15.4	Bcf	$4.61 Mcf	Basin Specific Swaps - San Juan
	2014	5	Bcf	$3.81 Mcf	Basin Specific Swaps - Permian
	2015	23	Bcf	$4.13 Mcf	Basin Specific Swaps - San Juan
	2015	6	Bcf	$4.20 Mcf	Basin Specific Swaps - Permian
	Natural Gas Basis Differential
	2014	3.1	Bcf	$(0.09) Mcf	San Juan Basis Swaps
	2014	1.2	Bcf	$(0.17) Mcf	Permian Basis Swaps
	*WTS - West Texas Sour/Midland, WTI - West Texas Intermediate/Cushing
	**WTI - West Texas Intermediate/Midland, WTI - West Texas Intermediate/Cushing

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Assets and Liabilities Measured at Fair Value on a Recurring Basis	'
	The following fair value hierarchy tables present information about Energen’s assets and liabilities measured at fair value on a recurring basis:
		June 30, 2014
	(in thousands)	Level 2			Level 3			Total
	Assets:
	Derivative instruments	$	(2,992	)	$	3,516		$	524
	Noncurrent derivative instruments	—			623			623
	Total assets	(2,992		)	4,139			1,147
	Liabilities:
	Derivative instruments	(95,999		)	(214		)	(96,213		)
	Noncurrent derivative instruments	(22,987		)	1,282			(21,705		)
	Total liabilities	(118,986		)	1,068			(117,918		)
	Net derivative asset (liability)	$	(121,978	)	$	5,207		$	(116,771	)
		31-Dec-13
	(in thousands)	Level 2			Level 3			Total
	Assets:
	Derivative instruments	$	(1,658	)	$	19,121		$	17,463
	Noncurrent derivative instruments	4,383			1,056			5,439
	Total assets	2,725			20,177			22,902
	Liabilities:
	Derivative instruments	(28,414		)	(1,888		)	(30,302		)
	Total liabilities	(28,414		)	(1,888		)	(30,302		)
	Net derivative asset (liability)	$	(25,689	)	$	18,289		$	(7,400	)
Schedule of Changes in Fair Value of Derivative Instruments Classified as Level 3	'
	The tables below set forth a summary of changes in the fair value of Energen’s Level 3 derivative commodity instruments as follows:
		Three months ended			Three months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Balance at beginning of period	$	1,378		$	26,459
	Realized gains	785			6,183
	Unrealized gains relating to instruments held at the reporting date*	3,800			23,404
	Settlements during period	(756		)	(4,915		)
	Balance at end of period	$	5,207		$	51,131
		Six months ended			Six months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Balance at beginning of period	$	18,289		$	89,019
	Realized gains (losses)	(2,158		)	32,368
	Unrealized losses relating to instruments held at the reporting date*	(13,111		)	(39,156		)
	Settlements during period	2,187			(31,100		)
	Balance at end of period	$	5,207		$	51,131
Schedule of Fair Value Inputs, Derivatives, Quantitative Information	'
	The tables below set forth quantitative information about the Energen’s Level 3 fair value measurements of derivative commodity instruments as follows:
	(in thousands, except price data)	Fair Value as of June 30, 2014			Valuation Technique*	Unobservable Input*	Range
	Oil Basis - WTS/WTI
	2014	$	1,119		Discounted Cash Flow	Forward Basis	($5.01) Bbl
	Oil Basis - WTI/WTI
	2014	$	3,072		Discounted Cash Flow	Forward Basis	($5.42 - $5.57) Bbl
	Natural Gas Liquids
	2014	$	91		Discounted Cash Flow	Forward Price	$0.74 - $0.97 Gal
	Natural Gas Basis - San Juan
	2014	$	2,817		Discounted Cash Flow	Forward Basis	($0.03 - $0.07) Mcf
	2015	$	579		Discounted Cash Flow	Forward Basis	($0.11 - $0.12) Mcf
	Natural Gas Basis - Permian
	2014	$	(3,073	)	Discounted Cash Flow	Forward Basis	($0.06 - $0.07) Mcf
	2015	$	602		Discounted Cash Flow	Forward Basis	($0.13) Mcf
	*Discounted cash flow represents an income approach in calculating fair value including the referenced unobservable input and a discount reflecting credit quality of the counterparty.

Reconciliation_of_Earnings_Per1

Reconciliation of Earnings Per Share (EPS) (Tables)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Schedule of Earnings Per Share Reconciliation	'
		Three months ended							Three months ended
	(in thousands, except per share amounts)	June 30, 2014							June 30, 2013
		Net				Per Share			Net			Per Share
		Income			Shares	Amount			Income		Shares	Amount
	Basic EPS	$	(7,953	)	72,851	$	(0.11	)	$	83,067	72,167	$	1.15
	Effect of dilutive securities
	Stock options				—						225
	Non-vested restricted stock				—						16
	Performance share awards				—						11
	Diluted EPS	$	(7,953	)	72,851	$	(0.11	)	$	83,067	72,419	$	1.15
	In periods of loss, shares that otherwise would have been included in diluted average common shares outstanding are excluded. Energen had 337,614 of excluded shares for the three months ended June 30, 2014.
		Six months ended							Six months ended
	(in thousands, except per share amounts)	June 30, 2014							June 30, 2013
		Net				Per Share			Net			Per Share
		Income			Shares	Amount			Income		Shares	Amount
	Basic EPS	$	45,363		72,737	$	0.62		$	139,759	72,155	$	1.94
	Effect of dilutive securities
	Stock options				165						164
	Non-vested restricted stock				48						10
	Performance share awards				81						—
	Diluted EPS	$	45,363		73,031	$	0.62		$	139,759	72,329	$	1.93
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	'
	Energen had the following shares that were excluded from the computation of diluted EPS, as inclusion would be anti-dilutive:
		Three months ended				Six months ended
		June 30,				June 30,
	(in thousands)	2014		2013		2014		2013
	Stock options	114		316		114		687
	Performance share awards	4		—		68		161

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2014
Pension Plans	'
Defined Benefit Plan Disclosure [Line Items]	'
Schedule of Net Benefit Costs	'
	The components of net periodic benefit cost for Energen’s defined benefit non-contributory pension plan and certain nonqualified supplemental pension plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	1,621		$	1,327		$	3,256		$	2,654
	Interest cost	1,404			1,088			2,817			2,176
	Expected long-term return on assets	(1,449		)	(1,323		)	(2,909		)	(2,645		)
	Actuarial loss	1,407			1,823			2,819			3,657
	Prior service cost amortization	57			62			114			123
	Settlement charge	115			—			3,673			144
	Net periodic expense	$	3,155		$	2,977		$	9,770		$	6,109
	The components of net periodic benefit cost for Alagasco’s two defined benefit non-contributory pension plans and allocated costs from the Energen nonqualified supplemental pension plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	1,696		$	2,176		$	3,393		$	4,352
	Interest cost	1,439			1,612			2,878			3,225
	Expected long-term return on assets	(1,679		)	(2,315		)	(3,359		)	(4,632		)
	Actuarial loss	1,110			1,937			2,220			3,878
	Prior service cost amortization	71			72			143			144
	Net periodic expense	$	2,637		$	3,482		$	5,275		$	6,967
Postretirement Benefit Plans	'
Defined Benefit Plan Disclosure [Line Items]	'
Schedule of Net Benefit Costs	'
	The components of net periodic postretirement benefit expense for Energen’s postretirement benefit plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	59		$	112		$	119		$	223
	Interest cost	224			176			450			351
	Expected long-term return on assets	(383		)	(214		)	(770		)	(426		)
	Actuarial loss	(209		)	—			(421		)	—
	Transition amortization	15			63			30			126
	Net periodic (income) expense	$	(294	)	$	137		$	(592	)	$	274
Alabama Gas Corporation | Postretirement Benefit Plans	'
Defined Benefit Plan Disclosure [Line Items]	'
Schedule of Net Benefit Costs	'
	The components of net periodic postretirement benefit (income) expense for Alagasco’s postretirement benefit plans were as follows:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	132		$	314		$	265		$	629
	Interest cost	614			664			1,227			1,328
	Expected long-term return on assets	(1,172		)	(994		)	(2,343		)	(1,989		)
	Actuarial loss	(388		)	—			(777		)	—
	Transition amortization	17			251			34			502
	Net periodic (income) expense	$	(797	)	$	235		$	(1,594	)	$	470

LongTerm_Debt_and_Notes_Payabl1

Long-Term Debt and Notes Payable (Tables)	6 Months Ended
	Jun. 30, 2014
Debt Instrument [Line Items]	'
Long-term debt	'
	Long-term debt consisted of the following:
	(in thousands)	June 30, 2014			December 31, 2013
	Energen:
	7.40% Medium-term Notes, Series A, due July 24, 2017	$	2,000		$	2,000
	7.36% Medium-term Notes, Series A, due July 24, 2017	15,000			15,000
	7.23% Medium-term Notes, Series A, due July 28, 2017	2,000			2,000
	7.32% Medium-term Notes, Series A, due July 28, 2022	20,000			20,000
	7.60% Medium-term Notes, Series A, due July 26, 2027	5,000			5,000
	7.35% Medium-term Notes, Series A, due July 28, 2027	10,000			10,000
	7.125% Medium-term Notes, Series B, due February 15, 2028	100,000			100,000
	4.625% Notes, due September 1, 2021	400,000			400,000
	Senior Term Loans, (floating rate interest LIBOR plus 1.625%; 1.775% at June 30, 2014), due September 30, 2014 to December 17, 2017	570,000			600,000
		1,124,000			1,154,000
	Less amounts due within one year	570,000			60,000
	Less unamortized debt discount	448			459
	Total Energen	$	553,552		$	1,093,541
	Alagasco:
	5.368% Notes, due December 1, 2015	$	80,000		$	80,000
	5.20% Notes, due January 15, 2020	40,000			40,000
	3.86% Notes, due December 21, 2021	50,000			50,000
	5.70% Notes, due January 15, 2035	34,830			34,923
	5.90% Notes, due January 15, 2037	45,000			45,000
		249,830			249,923
	Less amounts due within one year	50,000			—
	Total Alagasco (included in liabilities related to assets held for sale)	$	199,830		$	249,923
Summary of Credit Facilities	'
	The following is a summary of information relating to Energen’s credit facility:
	(in thousands)	June 30, 2014			December 31, 2013
	Energen notes payable to banks	$	669,000		$	489,000
	Available for borrowings	581,000			761,000
	Total Energen	$	1,250,000		$	1,250,000
	Energen maximum amount outstanding at any month-end	$	669,000		$	901,000
	Energen average daily amount outstanding	$	576,486		$	804,895
	Energen weighted average interest rates based on:
	Average daily amount outstanding	1.42		%	1.38		%
	Amount outstanding at period-end	1.4		%	1.32		%
Energen Corporation	'
Debt Instrument [Line Items]	'
Maturities of Long-term Debt	'
	The aggregate maturities of Energen’s long-term debt outstanding at June 30, 2014 are as follows:
	(in thousands)
	Remaining 2014	2015	2016	2017	2018	2019 and thereafter
	$570,000	—	—	$19,000	—	$535,000
Alabama Gas Corporation	'
Debt Instrument [Line Items]	'
Long-term debt	'
	Long-term debt consisted of the following:
	(in thousands)	June 30, 2014			December 31, 2013
	5.368% Notes, due December 1, 2015	$	80,000		$	80,000
	5.20% Notes, due January 15, 2020	40,000			40,000
	3.86% Notes, due December 21, 2021	50,000			50,000
	5.70% Notes, due January 15, 2035	34,830			34,923
	5.90% Notes, due January 15, 2037	45,000			45,000
		249,830			249,923
	Less amounts due within one year	50,000			—
	Total	$	199,830		$	249,923
Maturities of Long-term Debt	'
	The aggregate maturities of Alagasco’s long-term debt outstanding at June 30, 2014 are as follows:
	(in thousands)
	Remaining 2014	2015	2016	2017	2018	2019 and thereafter
	$50,000	$80,000	—	—	—	$119,830
Summary of Credit Facilities	'
	The following is a summary of information relating to the credit facility:
	(in thousands)	June 30, 2014			December 31, 2013
	Notes payable to banks	$	—		$	50,000
	Available for borrowings	100,000			50,000
	Total	$	100,000		$	100,000
	Alagasco maximum amount outstanding at any month-end	$	55,000		$	75,000
	Alagasco average daily amount outstanding	$	17,956		$	35,027
	Alagasco weighted average interest rates based on:
	Average daily amount outstanding	1.28		%	1.12		%
	Amount outstanding at period-end	—		%	1.26		%

Exploratory_Costs_Tables

Exploratory Costs (Tables)	6 Months Ended
	Jun. 30, 2014
Extractive Industries [Abstract]	'
Schedule of Capitalized Exploratory Wells	'
	The following table sets forth capitalized exploratory well costs and includes additions pending determination of proved reserves, reclassifications to proved reserves and costs charged to expense:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Capitalized exploratory well costs at beginning of period	$	109,968		$	106,175		$	57,600		$	79,791
	Additions pending determination of proved reserves	200,347			123,719			365,189			219,580
	Reclassifications due to determination of proved reserves	(142,666		)	(157,722		)	(255,140		)	(227,199		)
	Exploratory well costs charged to expense	(1,191		)	—			(1,191		)	—
	Capitalized exploratory well costs at end of period	$	166,458		$	72,172		$	166,458		$	72,172
	The following table sets forth capitalized exploratory wells costs and includes amounts capitalized for a period greater than one year:
		Six months ended			Six months ended
	(in thousands)	June 30, 2014			June 30, 2013
	Exploratory wells in progress	$	35,753		$	25,728
	Capitalized exploratory well costs capitalized for a period of one year or less	129,477			45,245
	Capitalized exploratory well costs for a period greater than one year	1,228			1,199
	Total capitalized exploratory well costs	$	166,458		$	72,172

Financial_Instruments_Tables

Financial Instruments (Tables) (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'
Allowance for Credit Losses on Financing Receivables	'
	The following table sets forth a summary of changes in the allowance for credit losses as follows:
	(in thousands)
	Allowance for credit losses as of December 31, 2013	$	423
	Provision	(118		)
	Allowance for credit losses as of June 30, 2014	$	305

Regulatory_Assets_and_Liabilit1

Regulatory Assets and Liabilities (Tables) (Alabama Gas Corporation)	6 Months Ended
	Jun. 30, 2014
Alabama Gas Corporation	'
Regulatory Assets and Liabilities [Line Items]	'
Schedule of Regulatory Assets and Liabilities	'
	The following table details regulatory assets and liabilities on the balance sheets:
	(in thousands)	June 30, 2014				31-Dec-13
		Current		Noncurrent		Current		Noncurrent
	Regulatory assets:
	Pension assets	$	1,284	$	65,627	$	325	$	58,243
	Accretion and depreciation of asset retirement obligations	—		18,825		—		18,046
	Rate recovery of asset removal costs, net	—		3,405		—		4,601
	Enhanced stability reserve	—		4,000		—		4,000
	Gas supply adjustment	—		—		2,406		—
	RSE adjustment	1,032		—		25		—
	Total regulatory assets	$	2,316	$	91,857	$	2,756	$	84,890
	Regulatory liabilities:
	RSE adjustment	$	18,578	$	—	$	4,690	$	—
	Unbilled service margin	6,445		—		28,504		—
	Postretirement liabilities	—		26,948		—		26,197
	Gas supply adjustment	25,985		—		—		—
	Refundable negative salvage	13,360		26,760		15,779		39,663
	Asset retirement obligation	—		28,152		—		27,528
	Other	33		720		33		737
	Total regulatory liabilities	$	64,401	$	82,580	$	49,006	$	94,125

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Schedule of Change in Asset Retirement Obligation	'
	The following table reflects the components of the change in Energen’s ARO balance for the six months ended June 30, 2014:
	(in thousands)
	Balance as of December 31, 2013	$	108,533
	Liabilities incurred	1,504
	Liabilities settled	(676		)
	Accretion expense	3,726
	Balance as of June 30, 2014	$	113,087

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	The following table provides changes in the components of accumulated other comprehensive income (loss), net of the related income tax effects.
	(in thousands)	Cash Flow Hedges			Pension and Postretirement Plans			Total
	Balance as of December 31, 2013	$	12,178		$	(32,245	)	$	(20,067	)
	Other comprehensive income (loss) before reclassifications	(287		)	(2,136		)	(2,423		)
	Amounts reclassified from accumulated other comprehensive income (loss)	(4,748		)	6,739			1,991
	Change in accumulated other comprehensive income (loss)	(5,035		)	4,603			(432		)
	Balance as of June 30, 2014	$	7,143		$	(27,642	)	$	(20,499	)
Reclassification out of Accumulated Other Comprehensive Income	'
	The following table provides details of the reclassifications out of accumulated other comprehensive income (loss).
		Three months ended			Three months ended
		30-Jun-14			30-Jun-13
	(in thousands)	Amounts Reclassified						Line Item Where Presented
	Gains (losses) on cash flow hedges:
	Commodity contracts	$	5,735		$	4,503		Gain (loss) on derivative instruments, net
	Interest rate swap	(1,588		)	(426		)	Interest expense
	Total cash flow hedges	4,147			4,077
	Income tax expense	(1,623		)	(1,562		)
	Net of tax	2,524			2,515
	Pension and postretirement plans:
	Transition obligation	(9		)	(74		)	General and administrative
	Prior service cost	(74		)	(78		)	General and administrative
	Actuarial losses	(1,289		)	(2,097		)	General and administrative
	Actuarial losses on settlement charges	(360		)	—			General and administrative
	Total pension and postretirement plans	(1,732		)	(2,249		)
	Income tax expense	606			788
	Net of tax	(1,126		)	(1,461		)
	Total reclassifications for the period	$	1,398		$	1,054
		Six months ended			Six months ended
		30-Jun-14			30-Jun-13
	(in thousands)	Amounts Reclassified						Line Item Where Presented
	Gains (losses) on cash flow hedges:
	Commodity contracts	$	9,789		$	21,792		Gain (loss) on derivative instruments, net
	Interest rate swap	(2,033		)	(836		)	Interest expense
	Total cash flow hedges	7,756			20,956
	Income tax expense	(3,008		)	(7,989		)
	Net of tax	4,748			12,967
	Pension and postretirement plans:
	Transition obligation	(19		)	(147		)	General and administrative
	Prior service cost	(148		)	(157		)	General and administrative
	Actuarial losses*	(2,580		)	(4,350		)	General and administrative
	Actuarial losses on settlement charges	(7,622		)	—			General and administrative
	Actuarial losses on settlement charges*	—			(375		)	Assets held for sale as of June 30, 2014 with prior period comparable
	Total pension and postretirement plans	(10,369		)	(5,029		)
	Income tax expense	3,630			1,761
	Net of tax	(6,739		)	(3,268		)
	Total reclassifications for the period	$	(1,991	)	$	9,699
	* In the first quarter of 2013, Energen incurred a settlement charge of $0.5 million for the payment of lump sums from the nonqualified supplemental retirement plans, of which $0.1 million was recognized in actuarial losses above and $0.4 million was recognized as a regulatory asset at Alagasco and reported in actuarial losses on settlement charges above.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Schedule of Discontinued Operations	'
	he table below provides a detail of these items included in income (loss) from discontinued operations at June 30, 2014:
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands)	2014			2013			2014			2013
	Alagasco net income (loss)	$	(615	)	$	(704	)	$	42,413		$	46,518
	Depreciation, depletion and amortization	(153		)	(147		)	(305		)	(294		)
	General and administrative	687			1,724			1,627			3,578
	Interest expense	(7,190		)	(3,288		)	(12,977		)	(6,109		)
	Other income	(228		)	(64		)	(347		)	(473		)
	Income tax expense (benefit)	2,603			671			4,538			1,247
	Alagasco income (loss) from discontinued operations	(4,896		)	(1,808		)	34,949			44,467
	Energen income (loss) from discontinued operations	97			2,453			(1,029		)	4,451
	Income (loss) from discontinued operations	$	(4,799	)	$	645		$	33,920		$	48,918
		Three months ended						Six months ended
		June 30,						June 30,
	(in thousands, except per share data)	2014			2013			2014			2013
	Natural gas distribution revenues	$	93,873		$	104,514		$	357,774		$	342,199
	Oil and natural gas revenues	390			18,562			5,211			37,225
	Total revenues	$	94,263		$	123,076		$	362,985		$	379,424
	Pretax income (loss) from discontinued operations	$	(7,797	)	$	967		$	54,519		$	78,775
	Income tax expense (benefit)	(2,998		)	322			20,599			29,857
	Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	33,920		$	48,918
	Loss on disposal of discontinued operations	$	—		$	—		$	(1,667	)	$	—
	Income tax benefit	—			—			(617		)	—
	Loss on Disposal of Discontinued Operations	$	—		$	—		$	(1,050	)	$	—
	Total Income (Loss) From Discontinued Operations	$	(4,799	)	$	645		$	32,870		$	48,918
	Diluted Earnings Per Average Common Share
	Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.67
	Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
	Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.67
	Basic Earnings Per Average Common Share
	Income (Loss) from Discontinued Operations	$	(0.07	)	$	0.01		$	0.46		$	0.68
	Loss on Disposal of Discontinued Operations	—			—			(0.01		)	—
	Total Income (Loss) From Discontinued Operations	$	(0.07	)	$	0.01		$	0.45		$	0.68
	The following tables detail held for sale properties by major classes of assets and liabilities:
	(in thousands)				June 30, 2014
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	11,807		$	—		$	—		$	11,807
	Accounts receivable*	50,285			—			—			50,285
	Inventories	39,950			—			—			39,950
	Utility plant	1,517,534			—			—			1,517,534
	Less accumulated depreciation	(624,704		)	—			—			(624,704		)
	Other property, net	40			—			—			40
	Other current assets*	16,462			—			—			16,462
	Other long-term assets	142,672			—			—			142,672
	Total assets held for sale	1,154,046			—			—			1,154,046
	Accounts payable	(38,646		)	(2,172		)	(1,856		)	(42,674		)
	Royalty payable	—			—			(1,284		)	(1,284		)
	Accrued taxes*	(29,337		)	—			—			(29,337		)
	Long-term debt due within one year	(50,000		)	—			—			(50,000		)
	Other current liabilities	(108,633		)	—			(2		)	(108,635		)
	Other long-term liabilities	(335,369		)	—			(2		)	(335,371		)
	Long-term debt	(199,830		)	—			—			(199,830		)
	Total liabilities held for sale	(761,815		)	(2,172		)	(3,144		)	(767,131		)
	Total net assets held for sale	$	392,231		$	(2,172	)	$	(3,144	)	$	386,915
	(in thousands)				31-Dec-13
		Alabama Gas Corporation			Black Warrior Basin			North Louisiana/East Texas			Total
	Cash	$	3,032		$	—		$	—		$	3,032
	Accounts receivable*	103,748			2,829			1,272			107,849
	Inventories	41,200			—			68			41,268
	Oil and gas properties	—			—			348,379			348,379
	Less accumulated depreciation, depletion and amortization	—						(301,609		)	(301,609		)
	Utility plant	1,491,433			—			—			1,491,433
Less accumulated depreciation	(605,924		)	—			—			(605,924		)
Other property, net	41			—			165			206
Other current assets*	29,458			—			—			29,458
Other long-term assets	128,780			—			—			128,780
Total assets held for sale	1,191,768			2,829			48,275			1,242,872
Accounts payable	(48,653		)	(1,732		)	(11		)	(50,396		)
Royalty payable	—			(550		)	(869		)	(1,419		)
Accrued taxes	(28,027		)	—			—			(28,027		)
Notes payable to banks	(50,000		)	—			—			(50,000		)
Other current liabilities*	(105,013		)	(379		)	(21		)	(105,413		)
Other long-term liabilities	(331,409		)	—			(14,983		)	(346,392		)
Long-term debt	(249,923		)	—			—			(249,923		)
Total liabilities held for sale	(813,025		)	(2,661		)	(15,884		)	(831,570		)
Total net assets held for sale	$	378,743		$	168		$	32,391		$	411,302

Organization_and_Basis_of_Pres3

Organization and Basis of Presentation - Derivative Gains and Losses (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) on derivative instruments, net	($84,846)	$55,244	($138,237)	$36,288
Commodity contracts	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Open non-cash mark-to-market gains (losses) on derivative instruments	-59,621	56,149	-93,302	15,101
Closed gains (losses) on derivative instruments	-25,225	-905	-44,935	21,187
Gain (loss) on derivative instruments, net	($84,846)	$55,244	($138,237)	$36,288

Organization_and_Basis_of_Pres4

Organization and Basis of Presentation (Details) (Alabama Gas Corporation, USD $)	1 Months Ended
	Apr. 30, 2014
Alabama Gas Corporation	'
Schedule of Quantifying Prior Year Misstatement Not Corrected Due to Materiality [Line Items]	'
Expected amount of consideration to be received	$1,600,000,000
Expected proceeds from sale of Alagasco	1,280,000,000
Expected amount of debt to be assigned	$320,000,000

Organization_and_Basis_of_Pres5

Organization and Basis of Presentation - Discontinued Operations (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'
Income (Loss) from Discontinued Operations	($4,799)	$645	$32,870	$48,918
Income (Loss) From Discontinued Operations	-4,799	645	33,920	48,918
Energen Corporation	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'
Income (Loss) from Discontinued Operations	97	2,453	-1,029	4,451
Alabama Gas Corporation	'	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'
Alagasco net income (loss)	-615	-704	42,413	46,518
Depreciation, depletion and amortization	-153	-147	-305	-294
General and administrative	687	1,724	1,627	3,578
Interest expense	-7,190	-3,288	-12,977	-6,109
Other income	-228	-64	-347	-473
Income tax expense (benefit)	2,603	671	4,538	1,247
Income (Loss) from Discontinued Operations	($4,896)	($1,808)	$34,949	$44,467

Regulatory_Matters_Details

Regulatory Matters (Details) (Alabama Gas Corporation, USD $)	0 Months Ended				3 Months Ended		6 Months Ended
	Jan. 02, 2014	Dec. 01, 2013	Nov. 05, 2013	Dec. 01, 2012	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Performance based adjustment on adjusting point	'	'	5.00%	'	'	'	'	'
Revenue reductions (increase) of rate adjustments	$8,500,000	($10,300,000)	'	($7,800,000)	$4,000,000	$3,800,000	$20,300,000	$6,300,000
Equity upon which a return will be permitted	'	'	56.50%	'	'	'	'	'
Approved increase	'	'	1.75%	'	'	'	'	'
Increase to revenue due to O&M expense below index range	'	'	'	'	1,000,000	'	'	'
Enhanced Stability Reserve refund period	'	'	'	'	'9 years	'	'	'
Enhanced Stability Reserve amortization period	'	'	'	'	'5 years	'	'	'
Enhanced Stability Reserve, amortization expense	'	'	'	'	'	'	660,000	'
APSC Approved Expension of ESR, November 1, 2010	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Large commercial and industrial customer budget minimum amount charged to Enhanced Stability Reserve	'	'	'	'	'	'	350,000	'
Force Majeure Event Costs | APSC Approved Expension of ESR, November 1, 2010	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Extraordinary operating and maintenance expenses minimum amount charged to Enhanced Stability Reserve	'	'	'	'	'	'	275,000	'
Force Majeure Events Costs | APSC Approved Expension of ESR, November 1, 2010	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Extraordinary operating and maintenance expenses minimum amount charged to Enhanced Stability Reserve	'	'	'	'	'	'	412,500	'
Self Insurance Costs | APSC Approved Expension of ESR, November 1, 2010	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Extraordinary operating and maintenance expenses minimum amount charged to Enhanced Stability Reserve	'	'	'	'	$1,000,000	'	'	'
Minimum	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Allowed return on average common equity	'	'	'	'	13.15%	'	'	'
Maximum	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Allowed return on average common equity	'	'	'	'	13.65%	'	'	'
Rate increases as percentage of prior year revenues	'	'	'	'	4.00%	'	'	'
APSC	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Adjusting point	'	'	10.80%	'	'	'	'	'
APSC | Minimum	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Approved return on equity	'	'	10.50%	'	'	'	'	'
APSC | Maximum	'	'	'	'	'	'	'	'
Regulatory Matters [Line Items]	'	'	'	'	'	'	'	'
Approved return on equity	'	'	10.95%	'	'	'	'	'

Derivative_Commodity_Instrumen2

Derivative Commodity Instruments - Commodity Contracts by Business Segment (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013
	counterparty		bbl	bbl
Derivative [Line Items]	'	'	'	'
Number of active counterparties with whom company holds net gain positions	2	'	'	'
Number of active counterparties with whom company holds net loss positions	12	'	'	'
Derivative assets	$1,147,000	$22,902,000	'	'
Notional Amount of Derivatives Transferred to Not Designated as Hedging Instruments	'	'	2,353,000	5,078,000
Net deferred tax liability	4,500,000	8,200,000	'	'
Cash Flow Hedging	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivative assets	$1,000,000	'	'	'

Derivative_Commodity_Instrumen3

Derivative Commodity Instruments - Offsetting Assets and Liabilities (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	$16,616	$44,215
Gross Amounts Offset in the Balance Sheets	-15,469	-21,313
Net Amount Presented in the Balance Sheets	1,147	22,902
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	1,147	22,902
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	133,387	51,615
Gross Amounts Offset in the Balance Sheets	-15,469	-21,313
Net Amount Presented in the Balance Sheets	117,918	30,302
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	117,918	30,302
Total Derivatives	-116,771	-7,400
Current Assets	'	'
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	14,540	36,223
Gross Amounts Offset in the Balance Sheets	-14,016	-18,760
Net Amount Presented in the Balance Sheets	524	17,463
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	524	17,463
Noncurrent Assets	'	'
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	2,076	7,992
Gross Amounts Offset in the Balance Sheets	-1,453	-2,553
Net Amount Presented in the Balance Sheets	623	5,439
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	623	5,439
Current Liabilities	'	'
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	110,229	49,062
Gross Amounts Offset in the Balance Sheets	-14,016	-18,760
Net Amount Presented in the Balance Sheets	96,213	30,302
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	96,213	30,302
Noncurrent Liabilities	'	'
Derivative assets	'	'
Gross Amounts Recognized at Fair Value	23,158	2,553
Gross Amounts Offset in the Balance Sheets	-1,453	-2,553
Net Amount Presented in the Balance Sheets	21,705	0
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Fair Value Presented in the Balance Sheets	$21,705	$0

Derivative_Commodity_Instrumen4

Derivative Commodity Instruments Derivatives commodity instruments - Cash flow hedging relationship in financial statements (Details) (Commodity contracts, USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Net gain (loss) recognized in other comprehensive income on derivatives (effective portion), net of tax of $7 and ($6,712)	$9	$15,847	$11	($10,951)
Current period change in fair value of interest rate swap, tax	6	9,713	7	-6,712
Gain (loss) on derivative instruments, net	'	'	'	'
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Gain reclassified from accumulated other comprehensive income into income (effective portion)	5,735	3,112	9,789	20,935
Gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	$0	$1,392	$0	$858

Derivative_Commodity_Instrumen5

Derivative Commodity Instruments Derivative Commodity instruments not designated as hedging instruments on the Income Statement (Details) (Gain (loss) on derivative instruments, net, USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Gain (loss) on derivative instruments, net	'	'	'	'
Derivative Instruments and Hedging Activities Disclosures [Line Items]	'	'	'	'
Gain (loss) recognized in income on derivatives	($90,581)	$53,078	($148,026)	$21,577

Derivative_Commodity_Instrumen6

Derivative Commodity Instruments Derivative Commodity - Reclassification (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivatives, Fair Value [Line Items]	'	'	'	'
Deferred net gains on derivative instruments recorded in accumulated other comprehensive income, net of tax	$7,300,000	'	'	'
Revenue, Net	270,097,000	366,981,000	567,375,000	603,312,000
Production Period, Year One | NYMEX Swaps | Crude Oil	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	4,958,000	'	4,958,000	'
Average contract price	'	'	92.65	'
Production Period, Year One | NYMEX Swaps | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	5,200,000	'	5,200,000	'
Average contract price ($ per Mcf)	'	'	4.56	'
Production Period, Year One | WTS/WTI Basis Swaps | Crude Oil	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	600,000	'	600,000	'
Average contract price	'	'	-3.3	'
Production Period, Year One | WTI/WTI Basis Swaps | Crude Oil	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	1,200,000	'	1,200,000	'
Average contract price	'	'	-3.08	'
Production Period, Year One | Liquids Swaps | Natural Gas Liquids	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	35,800,000	'	35,800,000	'
Average contract price	'	'	0.93	'
Production Period, Year One | Basin Specific Swaps, San Juan | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	15,400,000	'	15,400,000	'
Average contract price ($ per Mcf)	'	'	4.61	'
Production Period, Year One | Basin Specific Swaps - Permain | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	5,000,000	'	5,000,000	'
Average contract price ($ per Mcf)	'	'	3.81	'
Production Period, Year One | San Juan Basis Swaps | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	0	'	0	'
Average contract price ($ per Mcf)	'	'	-0.09	'
Production Period, Year One | Permian Basis Swaps | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	0	'	0	'
Average contract price ($ per Mcf)	'	'	-0.17	'
Production Period, Year Two | NYMEX Swaps | Crude Oil	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	8,280,000	'	8,280,000	'
Average contract price	'	'	89.3	'
Production Period, Year Two | Basin Specific Swaps, San Juan | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	23,000,000	'	23,000,000	'
Average contract price ($ per Mcf)	'	'	4.13	'
Production Period, Year Two | Basin Specific Swaps - Permain | Natural Gas	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Total Hedged Volumes	6,000,000	'	6,000,000	'
Average contract price ($ per Mcf)	'	'	4.2	'
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain from Discontinued Hedge Accounting [Member]	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Revenue, Net	'	'	$3,000,000	'

Fair_Value_Measurements_Recurr

Fair Value Measurements - Recurring Basis (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Noncurrent assets	$623	$5,439
Total asset	1,147	22,902
Total liabilities	-117,918	-30,302
Recurring	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Current assets	524	17,463
Noncurrent assets	623	5,439
Total asset	1,147	22,902
Current liabilities	-96,213	-30,302
Noncurrent derivative instruments	-21,705	'
Total liabilities	-117,918	-30,302
Net derivative asset (liability)	-116,771	-7,400
Recurring | Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Current assets	-2,992	-1,658
Noncurrent assets	0	4,383
Total asset	-2,992	2,725
Current liabilities	-95,999	-28,414
Noncurrent derivative instruments	-22,987	'
Total liabilities	-118,986	-28,414
Net derivative asset (liability)	-121,978	-25,689
Recurring | Level 3	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Current assets	3,516	19,121
Noncurrent assets	623	1,056
Total asset	4,139	20,177
Current liabilities	-214	-1,888
Noncurrent derivative instruments	1,282	'
Total liabilities	1,068	-1,888
Net derivative asset (liability)	$5,207	$18,289

Change_in_Fair_Value_Details

- Change in Fair Value (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Commodity Instruments	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Balance at beginning of period	$1,378,000	$26,459,000	$18,289,000	$89,019,000
Realized gains	785,000	6,183,000	-2,158,000	32,368,000
Unrealized losses relating to instruments held at the reporting date	3,800,000	23,404,000	-13,111,000	-39,156,000
Settlements during period	-756,000	-4,915,000	2,187,000	-31,100,000
Balance at end of period	5,207,000	51,131,000	5,207,000	51,131,000
Mark-to-market gain included in earnings, unrealized	5,200,000	'	4,200,000	'
Mark-to-market loss included in earnings, unrealized	'	8,500,000	'	2,700,000
Level 3	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Impact on fair value of a 10 percent increase or decrease in commodity prices	23,000,000	'	23,000,000	'
Impact on results of operations of a 10 percent increase or decrease in commodity prices	'	'	$23,000,000	'

Level_3_Measurements_of_Deriva

- Level 3 Measurements of Derivative Commodity Instruments (Details) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

In Thousands, unless otherwise specified

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Discounted Cash Flow Valuation Technique

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Level 3

Oil Basis - WTS/WTI

Oil Basis - WTI/WTI

Oil Basis - WTI/WTI

Oil Basis - WTI/WTI

Liquids Swaps

Liquids Swaps

Liquids Swaps

Natural Gas Basis - San Juan

Natural Gas Basis - San Juan

Natural Gas Basis - San Juan

Natural Gas Basis - San Juan

Natural Gas Basis - San Juan

Natural Gas Basis - San Juan

Natural Gas Basis - Permian

Natural Gas Basis - Permian

Natural Gas Basis - Permian

Natural Gas Basis - Permian

2014

2014

2014

2014

2014

2014

2014

2014

2014

2014

2015

2015

2015

2014

2014

2014

2015

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Fair Value Inputs, Derivatives, Quantitative Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative assets

$1,147

$22,902

$1,119

$3,072

'

'

$91

'

'

$2,817

'

'

$579

'

'

'

'

'

$602

Derivative liabilities

($117,918)

($30,302)

'

'

'

'

'

'

'

'

'

'

'

'

'

($3,073)

'

'

'

Fair Value Inputs, Price Per Barrel

'

'

5.01

'

5.42

5.57

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair Value Inputs, Price Per Gallon

'

'

'

'

'

'

'

0.74

0.97

'

'

'

'

'

'

'

'

'

'

Fair Value Inputs, Price Per Cubic Foot

'

'

'

'

'

'

'

'

'

'

0.03

0.07

'

0.01

0.12

'

0.06

0.07

0.13

Fair_Value_Measurements_Narrat

Fair Value Measurements -Narratives (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Long-term debt fair value	$1,148,700,000	$1,161,900,000
Reported Value Measurement	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Long-term debt fair value	1,124,000,000	1,154,000,000
Alabama Gas Corporation | Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Long-term debt fair value	266,600,000	258,800,000
Alabama Gas Corporation | Reported Value Measurement	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Long-term debt fair value	249,800,000	249,900,000
Senior Loans | Swap	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest rate	2.67%	'
Senior Loans | Swap | Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest rate cash flow hedge liability at fair value	1,400,000	1,800,000
Senior Loans | Senior Term Loans, Due March 31, 2014 to November 29, 2016 | Swap	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Face amount	$190,000,000	'

Reconciliation_of_Earnings_Per2

Reconciliation of Earnings Per Share (EPS) - Earnings Per Share Reconciliation (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share Reconciliation	'	'	'	'
Net Income, Basic EPS	($7,953)	$83,067	$45,363	$139,759
Basic Shares Outstanding (in shares)	72,851	72,167	72,737	72,155
Earnings Per Share, Basic (in dollars per share)	($0.11)	$1.15	$0.62	$1.94
Effect of dilutive securities	'	'	'	'
Net Income, Diluted EPS	($7,953)	$83,067	$45,363	$139,759
Diluted Shares Outstanding (in shares)	72,851	72,419	73,031	72,329
Earnings Per Share, Diluted (dollars per share)	($0.11)	$1.15	$0.62	$1.93
Stock options	'	'	'	'
Effect of dilutive securities	'	'	'	'
Incremental common shares attributable to share-based payment arrangements	0	225	165	164
Non-vested restricted stock	'	'	'	'
Effect of dilutive securities	'	'	'	'
Incremental common shares attributable to share-based payment arrangements	0	16	48	10
Performance share awards	'	'	'	'
Effect of dilutive securities	'	'	'	'
Incremental common shares attributable to share-based payment arrangements	0	0	81	0

Reconciliation_of_Earnings_Per3

Reconciliation of Earnings Per Share (EPS) - Antidilutive Securities (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share, amount	337,614	'	'	'
Stock options	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share, amount	114,000	316,000	114,000	687,000
Performance share awards	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive securities excluded from computation of earnings per share, amount	4,000	0	68,000	161,000

Stock_Compensation_Details

Stock Compensation (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

In Millions, except Share data, unless otherwise specified

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2014

Mar. 31, 2014

Mar. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Jan. 31, 2013

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Stock options

Stock options

Stock options

Performance share awards

Performance share awards

Performance share awards

Performance share awards

Performance share awards

Performance share awards

Stock Appreciation Rights (SARs)

Stock Appreciation Rights (SARs)

Stock Appreciation Rights (SARs)

Restricted Stock Units (RSUs)

Restricted Stock Units (RSUs)

Restricted Stock Units (RSUs)

Restricted Stock Units (RSUs)

Restricted Stock Units (RSUs)

Deferred Compensation

Deferred Compensation

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Petrotech Incentive Plan

Petrotech Incentive Plan

Stock Compensation Plan

Stock Compensation Plan

Stock Compensation Plan

Petrotech Incentive Plan

Petrotech Incentive Plan

2 year vesting period

2 year vesting period

3 year vesting period

3 year vesting period

2 year vesting period

3 year vesting period

3 year vesting period

Share-based Compensation Arrangement by Share-based Payment Award

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Vesting period

'

'

'3 years

'

'2 years

'

'3 years

'

'3 years

'

'

'3 years

'

'

'3 years

'

'

'

'

Expiration period

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Grants in period, options

2,439

107,868

'

'

'

'

'

'

'

'

'

'

6,312

'

'

'

'

'

'

Grants in period, options, fair value

$32.22

$27.57

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Grants in period (in shares)

'

'

'

650

287

1,467

63,842

36,920

'

'

62,749

'

'

41,664

928

28,840

'

'

'

Grant date fair value

'

'

'

'

'

'

'

'

'

'

'

'

$78.99

'

$79.15

'

'

'

'

Grants in period, fair value (in dollars per share)

'

'

'

$137.11

$118.99

$109.02

$93.13

'

$122.39

$42.54

'

'

'

$70.68

'

'

$88.55

'

'

Noncash payments for repurchase of common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0

$0.30

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)

1 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

Jan. 31, 2014

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Mar. 31, 2014

Mar. 31, 2013

Jun. 30, 2014

Jan. 31, 2014

Jun. 30, 2014

Mar. 31, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Mar. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Supplemental Employee Retirement Plan

Supplemental Employee Retirement Plan

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

pension_plan

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Supplemental Employee Retirement Plan

Pension Plans

Pension Plans

Pension Plans

Pension Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Postretirement Benefit Plans

Defined Benefit Plan Disclosure [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of defined benefit non-contributory pension plans and certain nonqualified supplemental pension plans

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Components of net periodic benefit cost:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Service cost

'

$1,621,000

'

$1,327,000

$3,256,000

$2,654,000

$59,000

$112,000

$119,000

$223,000

'

'

'

'

$1,696,000

'

$2,176,000

$3,393,000

$4,352,000

$132,000

$314,000

$265,000

$629,000

'

'

'

'

'

'

'

'

'

Interest cost

'

1,404,000

'

1,088,000

2,817,000

2,176,000

224,000

176,000

450,000

351,000

'

'

'

'

1,439,000

'

1,612,000

2,878,000

3,225,000

614,000

664,000

1,227,000

1,328,000

'

'

'

'

'

'

'

'

'

Expected long-term return on assets

'

-1,449,000

'

-1,323,000

-2,909,000

-2,645,000

-383,000

-214,000

-770,000

-426,000

'

'

'

'

-1,679,000

'

-2,315,000

-3,359,000

-4,632,000

-1,172,000

-994,000

-2,343,000

-1,989,000

'

'

'

'

'

'

'

'

'

Actuarial loss

'

1,407,000

'

1,823,000

2,819,000

3,657,000

-209,000

0

-421,000

0

'

'

'

'

1,110,000

'

1,937,000

2,220,000

3,878,000

-388,000

0

-777,000

0

'

'

'

'

'

'

'

'

'

Prior service cost amortization

'

57,000

'

62,000

114,000

123,000

'

'

'

'

'

'

'

'

71,000

'

72,000

143,000

144,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Settlement charge

'

115,000

'

0

3,673,000

144,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Transition amortization

'

'

'

'

'

'

15,000

63,000

30,000

126,000

'

'

'

'

'

'

'

'

'

17,000

251,000

34,000

502,000

'

'

'

'

'

'

'

'

'

Net periodic expense

'

3,155,000

'

2,977,000

9,770,000

6,109,000

-294,000

137,000

-592,000

274,000

'

'

'

'

2,637,000

'

3,482,000

5,275,000

6,967,000

-797,000

235,000

-1,594,000

470,000

'

2,637,000

3,482,000

5,275,000

6,967,000

-797,000

235,000

-1,594,000

470,000

Estimated required future employer contributions in current fiscal year

'

1,600,000

'

'

1,600,000

'

'

'

'

'

'

'

'

'

2,900,000

'

'

2,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Contributions by employer in current fiscal year

1,600,000

'

'

'

'

'

'

'

'

'

'

'

'

1,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Benefit payments made in current fiscal year

'

33,000

'

'

913,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated future benefit payments in current fiscal year

'

5,200,000

'

'

5,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Settlement charges

'

700,000

'

'

'

'

'

'

'

'

400,000

500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Settlement charges expensed

'

400,000

6,900,000

'

'

'

'

'

'

'

'

100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Settlements recognized as a pension asset

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$300,000

$10,200,000

'

'

'

'

'

'

'

$400,000

'

'

'

'

'

'

'

'

Commitments_and_Contingencies_

Commitments and Contingencies - Commitments and Agreements (Details) (USD $)	1 Months Ended			6 Months Ended				6 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
	Alabama Gas Corporation	Alabama Gas Corporation	Crude Oil and Natural Gas	Natural Gas, Delivery and Storage	Natural Gas, Delivery and Storage	Natural Gas	Wholly Owned Properties	Mitchell County, Texas [Member]
	site	site	MBoe	Alabama Gas Corporation	Alabama Gas Corporation	Alabama Gas Corporation	Alabama Gas Corporation	pit
						Mcf	site
Long-term Purchase Commitment [Line Items]	'	'	'	'	'	'	'	'
Remaining contractual volume	'	'	6,000	'	'	'	'	'
Long-term purchase commitment	'	'	'	$140	'	'	'	'
Long-term purchase commitment, time period	'	'	'	'September 2024	'	'August 2020	'	'
Long-term commitments expense recognized in statement of operations	'	'	'	23.5	26	'	'	'
Long-term purchase commitment minimum quantity required	'	'	'	'	'	115,000,000	'	'
Recorded unconditional purchase obligation	'	'	'	'	'	0.3	'	'
Recorded unconditional purchase obligation, time period	'	'	'	'	'	'December 2014	'	'
Recorded unconditional purchase obligation, market value	'	'	'	'	'	0.3	'	'
Chain of title, manufactured gas plant sites	'	9	'	'	'	'	4	'
Chain of title, manufactured gas distribution sites	'	5	'	'	'	'	1	'
Environmental matters, number of sites	'	'	'	'	'	'	'	9
Anticipated environmental costs	'	'	'	'	'	'	'	3.4
Environmental costs paid	'	'	'	'	'	'	'	1.9
Accrued environmental costs	'	'	'	'	'	'	'	0.5
Preliminary estimate of estimate for further remediation	'	'	'	'	'	'	'	$1
Number of residence that purportedly exceed certain risk levels for contamination	50	'	'	'	'	'	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies - New Mexico Audits (Details) (USD $)	Jun. 30, 2014
Unfavorable Regulatory Action	'
Loss Contingencies [Line Items]	'
Minimum loss contingency range of loss	$142,000
Maximum loss contingency range of possible loss	$23,000,000
New Mexico	'
Loss Contingencies [Line Items]	'
Number of counties ONRR has ordered to restructure accounting on federal leases	2

LongTerm_Debt_and_Notes_Payabl2

Long-Term Debt and Notes Payable - Long-Term Debt (Details) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

In Thousands, unless otherwise specified

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Energen Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

London Interbank Offered Rate (LIBOR)

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Medium-term Notes

Notes Payable

Notes Payable

Senior Term Loans

Senior Term Loans

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Notes Payable

Energen Corporation

7.40% Medium-term Notes, Series A, due July 24, 2017

7.40% Medium-term Notes, Series A, due July 24, 2017

7.36% Medium-term Notes, Series A, due July 24, 2017

7.36% Medium-term Notes, Series A, due July 24, 2017

7.23% Medium-term Notes, Series A, due July 28, 2017

7.23% Medium-term Notes, Series A, due July 28, 2017

7.32% Medium-term Notes, Series A, due July 28, 2022

7.32% Medium-term Notes, Series A, due July 28, 2022

7.60% Medium-term Notes, Series A, due July 26, 2027

7.60% Medium-term Notes, Series A, due July 26, 2027

7.35% Medium-term Notes, Series A, due July 28, 2027

7.35% Medium-term Notes, Series A, due July 28, 2027

7.125% Medium-term Notes, Series B, due February 15, 2028

7.125% Medium-term Notes, Series B, due February 15, 2028

4.625% Notes, due September 1, 2021

4.625% Notes, due September 1, 2021

Senior Term Loans, (floating rate interest LIBOR plus 1.625%; 1.775% at June 30, 2014), due September 30, 2014 to December 17, 2017

Senior Term Loans, (floating rate interest LIBOR plus 1.625%; 1.775% at June 30, 2014), due September 30, 2014 to December 17, 2017

5.368% Notes, due December 1, 2015

5.368% Notes, due December 1, 2015

5.20% Notes, due January 15, 2020

5.20% Notes, due January 15, 2020

5.70% Notes, due January 15, 2035

5.70% Notes, due January 15, 2035

3.86% Notes, due December 21, 2021

3.86% Notes, due December 21, 2021

5.90% Notes, due January 15, 2037

5.90% Notes, due January 15, 2037

Senior Term Loans

Senior Term Loans, (floating rate interest LIBOR plus 1.625%; 1.775% at June 30, 2014), due September 30, 2014 to December 17, 2017

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross amount

'

'

$1,124,000

$1,154,000

$2,000

$2,000

$15,000

$15,000

$2,000

$2,000

$20,000

$20,000

$5,000

$5,000

$10,000

$10,000

$100,000

$100,000

$400,000

$400,000

$570,000

$600,000

$249,830

$249,923

$80,000

$80,000

$40,000

$40,000

$34,830

$34,923

$50,000

$50,000

$45,000

$45,000

'

Less amounts due within one year

570,000

60,000

570,000

60,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50,000

0

'

'

'

'

'

'

'

'

'

'

'

Less unamortized debt discount

'

'

448

459

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt

$553,552

$1,093,541

$553,552

$1,093,541

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$199,830

$249,923

'

'

'

'

'

'

'

'

'

'

'

Interest Rate

'

'

'

'

7.40%

'

7.36%

'

7.23%

'

7.32%

'

7.60%

'

7.35%

'

7.13%

'

4.63%

'

'

'

'

'

5.37%

'

5.20%

'

5.70%

'

3.86%

'

5.90%

'

'

Floating rate interest spread

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.63%

Interest rate at period end

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.78%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

LongTerm_Debt_and_Notes_Payabl3

Long-Term Debt and Notes Payable - Maturities of Long-Term Debt (Details) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Energen Corporation	'
Debt Instrument [Line Items]	'
Remaining 2014	$570,000
2015	0
2016	0
2017	19,000
2018	0
2019 and thereafter	535,000
Alabama Gas Corporation	'
Debt Instrument [Line Items]	'
Remaining 2014	50,000
2015	80,000
2016	0
2017	0
2018	0
2019 and thereafter	$119,830

LongTerm_Debt_and_Notes_Payabl4

Long-Term Debt and Notes Payable - Credit Facilities (Details) (USD $)	6 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Energen Corporation	'	'
Line of Credit Facility [Line Items]	'	'
Notes payable to banks	$669,000	$489,000
Available for borrowings	581,000	761,000
Total Energen	1,250,000	1,250,000
Maximum amount outstanding at any month-end	669,000	901,000
Average daily amount outstanding	576,486	804,895
Average daily amount outstanding interest rate	1.42%	1.38%
Amount outstanding at period-end interest rate	1.40%	1.32%
Alabama Gas Corporation	'	'
Line of Credit Facility [Line Items]	'	'
Notes payable to banks	0	50,000
Available for borrowings	100,000	50,000
Total Energen	100,000	100,000
Maximum amount outstanding at any month-end	55,000	75,000
Average daily amount outstanding	$17,956	$35,027
Average daily amount outstanding interest rate	1.28%	1.12%
Amount outstanding at period-end interest rate	0.00%	1.26%

LongTerm_Debt_and_Notes_Payabl5

Long-Term Debt and Notes Payable - Narratives (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Oct. 30, 2012

Oct. 30, 2012

Jun. 30, 2014

Jun. 30, 2014

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Energen Corporation

Energen Corporation

Minimum

Minimum

Maximum

Maximum

Syndicated Credit Facility

Syndicated Credit Facility

Syndicated Credit Facility

APSC Authorized Short-term Line of Credit

Senior Loans

Alabama Gas Corporation

Alabama Gas Corporation

Alabama Gas Corporation

Energen Corporation

Energen Corporation

Alabama Gas Corporation

Senior Term Loans due March 31, 2014 to December 17, 2017

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long term debt

'

'

'

'

'

'

'

'

'

$600,000,000

'

'

'

'

'

'

'

'

Cross default provision, threshold amount

'

'

'

'

10,000,000

'

10,000,000

'

10,000,000

'

'

'

'

'

'

'

'

'

Maximum borrowing capacity

100,000,000

'

100,000,000

'

'

'

'

'

'

'

'

'

'

'

100,000,000

1,250,000,000

'

'

Debt instrument term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'5 years

'

Authorized amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

200,000,000

Maximum consolidated debt to capitalization ratio

'

'

'

'

65.00%

'

65.00%

'

65.00%

'

'

'

'

'

'

'

'

'

Credit facility cross default provision, threshold amount

'

'

'

'

50,000,000

'

50,000,000

'

50,000,000

'

'

'

'

'

'

'

'

'

Interest expense

7,964,000

10,182,000

15,852,000

20,083,000

3,745,000

3,833,000

7,710,000

7,863,000

'

'

'

'

'

'

'

'

'

'

Capitalized interest expense

$37,000

$34,000

$37,000

$200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Commitment fee percentage on the unused portion of available credit facilities

'

'

'

'

'

'

'

'

'

'

0.15%

0.15%

0.25%

0.25%

'

'

'

'

Exploratory_Costs_Details

Exploratory Costs (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
	well		well
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]	'	'	'	'
Capitalized exploratory well costs at beginning of period	$109,968	$106,175	$57,600	$79,791
Additions pending determination of proved reserves	200,347	123,719	365,189	219,580
Reclassifications due to determination of proved reserves	-142,666	-157,722	-255,140	-227,199
Exploratory well costs charged to expense	-1,191	0	-1,191	0
Capitalized exploratory well costs at end of period	166,458	72,172	166,458	72,172
Exploratory wells in progress	35,753	25,728	35,753	25,728
Capitalized exploratory well costs capitalized for a period of one year or less	129,477	45,245	129,477	45,245
Capitalized exploratory well costs for a period greater than one year	1,228	1,199	1,228	1,199
Total capitalized exploratory well costs	$166,458	$72,172	$166,458	$72,172
Number of wells in process of drilling	56	'	56	'
Number of gross well capitalized greater than a year which is pending results from completion and testing	1	'	1	'

Financial_Instruments_Details

Financial Instruments (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Alabama Gas Corporation	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Financing receivable	$10,600,000	$10,600,000	$10,800,000
Financing receivable recorded investment average balance	3,000	3,000	'
Average finance receivable term	'	'84 months	'
Time after which delinquent accounts are evaluated	'90 days	'	'
Financing receivable recorded investment, equal to greater than 90 days past due	300,000	300,000	400,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]	'	'	'
Allowance for credit losses as of December 31, 2013	'	423,000	'
Provision	'	-118,000	'
Allowance for credit losses as of June 30, 2014	305,000	305,000	'
Fair Value	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Long-term debt fair value	1,148,700,000	1,148,700,000	1,161,900,000
Fair Value | Alabama Gas Corporation	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Long-term debt fair value	266,600,000	266,600,000	258,800,000
Reported Value Measurement	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Long-term debt fair value	1,124,000,000	1,124,000,000	1,154,000,000
Reported Value Measurement | Alabama Gas Corporation	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Long-term debt fair value	$249,800,000	$249,800,000	$249,900,000

Regulatory_Assets_and_Liabilit2

Regulatory Assets and Liabilities (Details) (Alabama Gas Corporation, USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	$2,316	$2,756
Regulatory assets, noncurrent	91,857	84,890
Regulatory liability, current	64,401	49,006
Regulatory liability, noncurrent	82,580	94,125
RSE adjustment	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	18,578	4,690
Regulatory liability, noncurrent	0	0
Unbilled service margin	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	6,445	28,504
Regulatory liability, noncurrent	0	0
Postretirement liabilities	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	0	0
Regulatory liability, noncurrent	26,948	26,197
Gas supply adjustment	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	25,985	0
Regulatory liability, noncurrent	0	0
Refundable negative salvage	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	13,360	15,779
Regulatory liability, noncurrent	26,760	39,663
Accretion and depreciation for asset retirement obligation	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	0	0
Regulatory liability, noncurrent	28,152	27,528
Other	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory liability, current	33	33
Regulatory liability, noncurrent	720	737
Pension and postretirement assets	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	1,284	325
Regulatory assets, noncurrent	65,627	58,243
Accretion and depreciation for asset retirement obligation	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	0	0
Regulatory assets, noncurrent	18,825	18,046
Rate recovery of asset removal costs, net	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	0	0
Regulatory assets, noncurrent	3,405	4,601
Enhanced Stability Reserve [Member]	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	0	0
Regulatory assets, noncurrent	4,000	4,000
Gas supply adjustment	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	0	2,406
Regulatory assets, noncurrent	0	0
RSE adjustment	'	'
Regulatory Assets and Liabilities [Line Items]	'	'
Regulatory assets, current	1,032	25
Regulatory assets, noncurrent	$0	$0

Asset_Retirement_Obligations_D

Asset Retirement Obligations (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013
					Alabama Gas Corporation	Alabama Gas Corporation	Asset removal costs	Asset removal costs
							Alabama Gas Corporation	Alabama Gas Corporation
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'	'	'	'	'	'	'	'
Balance as of December 31, 2013	'	'	$108,533	'	$28,200	$27,500	'	'
Liabilities incurred	'	'	1,504	'	'	'	'	'
Liabilities settled	'	'	-676	'	'	'	'	'
Accretion of discount on asset retirement obligations	1,883	1,729	3,726	3,416	'	'	'	'
Balance as of June 30, 2014	113,087	'	113,087	'	28,200	27,500	'	'
Regulatory assets, noncurrent	'	'	'	'	$91,857	$84,890	$3,405	$4,601

Rollforward_of_Accumulated_Oth

Rollforward of Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'
Balance as of December 31, 2013	($20,067)
Other comprehensive income (loss) before reclassifications	-2,423
Amounts reclassified from accumulated other comprehensive income (loss)	1,991
Change in accumulated other comprehensive income (loss)	-432
Balance as of June 30, 2014	-20,499
Cash Flow Hedges	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'
Balance as of December 31, 2013	12,178
Other comprehensive income (loss) before reclassifications	-287
Amounts reclassified from accumulated other comprehensive income (loss)	-4,748
Change in accumulated other comprehensive income (loss)	-5,035
Balance as of June 30, 2014	7,143
Pension and Postretirement Plans	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'
Balance as of December 31, 2013	-32,245
Other comprehensive income (loss) before reclassifications	-2,136
Amounts reclassified from accumulated other comprehensive income (loss)	6,739
Change in accumulated other comprehensive income (loss)	4,603
Balance as of June 30, 2014	($27,642)

Reclassifications_of_Accumulat

Reclassifications of Accumulated Other Comprehensive Income (Details) (USD $)

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2013

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Pension and Postretirement Plans

Pension and Postretirement Plans

Pension and Postretirement Plans

Pension and Postretirement Plans

Commodity contracts

Commodity contracts

Commodity contracts

Commodity contracts

Interest rate swap

Interest rate swap

Interest rate swap

Interest rate swap

Supplemental Employee Retirement Plan

Supplemental Employee Retirement Plan

Supplemental Employee Retirement Plan

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Cash Flow Hedges

Alabama Gas Corporation

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Reclassification out of Accumulated Other Comprehensive Income

Gains (losses) on cash flow hedges:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reclassification Adjustment from AOCI on Derivatives

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$5,735,000

$4,503,000

$9,789,000

$21,792,000

($1,588,000)

($426,000)

($2,033,000)

($836,000)

'

'

'

Total

'

'

'

'

'

'

'

'

4,147,000

4,077,000

7,756,000

20,956,000

-1,732,000

-2,249,000

-10,369,000

-5,029,000

'

'

'

'

'

'

'

'

'

'

'

Income tax expense

1,016,000

-46,229,000

-7,232,000

-50,273,000

'

'

'

'

-1,623,000

-1,562,000

-3,008,000

-7,989,000

606,000

788,000

3,630,000

1,761,000

'

'

'

'

'

'

'

'

'

'

'

Net of tax

'

'

'

'

1,398,000

1,054,000

-1,991,000

9,699,000

2,524,000

2,515,000

4,748,000

12,967,000

-1,126,000

-1,461,000

-6,739,000

-3,268,000

'

'

'

'

'

'

'

'

'

'

'

Pension and postretirement plans:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Transition obligation

'

'

'

'

'

'

'

'

'

'

'

'

-9,000

-74,000

-19,000

-147,000

'

'

'

'

'

'

'

'

'

'

'

Prior service cost

'

'

'

'

'

'

'

'

'

'

'

'

-74,000

-78,000

-148,000

-157,000

'

'

'

'

'

'

'

'

'

'

'

Actuarial losses

'

'

'

'

'

'

'

'

'

'

'

'

-1,289,000

-2,097,000

-2,580,000

-4,350,000

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss) on Settlement Charges, Operation, before Tax

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-7,622,000

0

'

'

'

'

'

'

'

'

'

'

'

Actuarial losses on settlement charges

'

'

'

'

'

'

'

'

'

'

'

'

-360,000

0

0

-375,000

'

'

'

'

'

'

'

'

'

'

'

Settlement charges

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

400,000

500,000

'

Settlement charges expensed

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000

'

Settlements recognized as a pension asset

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$400,000

Discontinued_Operations_Narrat

Discontinued Operations Narrative (Details) (USD $)	3 Months Ended					1 Months Ended		1 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2013	Oct. 31, 2013	Dec. 31, 2012	Apr. 30, 2014
	North Louisiana and East Texas Natural Gas and Oil Properties	North Louisiana and East Texas Natural Gas and Oil Properties	North Louisiana and East Texas Natural Gas and Oil Properties	North Louisiana and East Texas Natural Gas and Oil Properties	North Louisiana and East Texas Natural Gas and Oil Properties	Black Warrior Basin Properties	Black Warrior Basin Properties	Alabama Gas Corporation
				Natural Gas	Oil	Alabama	Alabama
				Bcf	MBbls		Natural Gas
							Mcf
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'	'
Expected amount of consideration to be received	'	'	'	'	'	'	'	$1,600,000,000
Expected proceeds from sale of Alagasco	'	'	'	'	'	'	'	1,280,000,000
Expected amount of debt to be assigned	'	'	'	'	'	'	'	320,000,000
Sale price of gas and oil properties	30,300,000	'	'	'	'	'	'	'
Impairment of oil and gas properties held-for-sale	1,700,000	5,200,000	24,600,000	'	'	'	'	'
Proved Developed Reserves (Volume)	'	'	'	23,000,000	91	'	97,000,000	'
Proceeds from the sale of oil and gas property	'	'	'	'	'	160,000,000	'	'
Gain on disposition of oil and gas property	'	'	'	'	'	$35,000,000	'	'

Discontinued_Operations_Balanc

Discontinued Operations Balance Sheet and Income Statement (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Assets of Disposal Group, Including Discontinued Operation [Abstract]	'	'	'	'	'
Cash	$11,807,000	'	$11,807,000	'	$3,032,000
Accounts receivable	50,285,000	'	50,285,000	'	107,849,000
Inventories	39,950,000	'	39,950,000	'	41,268,000
Oil and gas properties	'	'	'	'	348,379,000
Less accumulated depreciation, depletion and amortization	-624,704,000	'	-624,704,000	'	-301,609,000
Utility plant	1,517,534,000	'	1,517,534,000	'	1,491,433,000
Less accumulated depreciation	'	'	'	'	-605,924,000
Other property, net	40,000	'	40,000	'	206,000
Other current assets	16,462,000	'	16,462,000	'	29,458,000
Other long-term assets	142,672,000	'	142,672,000	'	128,780,000
Total assets held for sale	1,154,046,000	'	1,154,046,000	'	1,242,872,000
Total assets held for sale	'	'	'	'	'
Accounts payable	-42,674,000	'	-42,674,000	'	-50,396,000
Royalty payable	-1,284,000	'	-1,284,000	'	-1,419,000
Accrued taxes	-29,337,000	'	-29,337,000	'	-28,027,000
Long-term debt due within one year	-50,000,000	'	-50,000,000	'	'
Notes payable to banks	'	'	'	'	-50,000,000
Other current liabilities	-108,635,000	'	-108,635,000	'	-105,413,000
Other long-term liabilities	-335,371,000	'	-335,371,000	'	-346,392,000
Long-term debt	-199,830,000	'	-199,830,000	'	-249,923,000
Total liabilities held for sale	-767,131,000	'	-767,131,000	'	-831,570,000
Total net assets held for sale	386,915,000	'	386,915,000	'	411,302,000
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]	'	'	'	'	'
Natural gas distribution revenues	93,873,000	104,514,000	357,774,000	342,199,000	'
Oil and natural gas revenues	390,000	18,562,000	5,211,000	37,225,000	'
Total revenues	94,263,000	123,076,000	362,985,000	379,424,000	'
Pretax income (loss) from discontinued operations	-7,797,000	967,000	54,519,000	78,775,000	'
Income tax expense (benefit)	-2,998,000	322,000	20,599,000	29,857,000	'
Income (Loss) From Discontinued Operations	-4,799,000	645,000	33,920,000	48,918,000	'
Loss on disposal of discontinued operations	0	0	-1,667,000	0	'
Income tax benefit	0	0	-617,000	0	'
Loss on Disposal of Discontinued Operations	0	0	-1,050,000	0	'
Total Income (Loss) From Discontinued Operations	-4,799,000	645,000	32,870,000	48,918,000	'
Diluted Earnings Per Average Common Share	'	'	'	'	'
Income (Loss) from Discontinued Operations (in dollars per share)	($0.07)	$0.01	$0.46	$0.67	'
Loss on Disposal of Discontinued Operations (in dollars per share)	$0	$0	($0.01)	$0	'
Total Income (Loss) From Discontinued Operations (in dollars per share)	($0.07)	$0.01	$0.45	$0.67	'
Basic Earnings Per Average Common Share	'	'	'	'	'
Income (Loss) from Discontinued Operations (in dollars per share)	($0.07)	$0.01	$0.46	$0.68	'
Loss on Disposal of Discontinued Operations (in dollars per share)	$0	$0	($0.01)	$0	'
Total Income (Loss) From Discontinued Operations (in dollars per share)	($0.07)	$0.01	$0.45	$0.68	'
Adjustment for affiliated companies receivables	'	13,200,000	'	13,200,000	4,700,000
Reclassification from accrued taxes to other current assets	'	7,900,000	'	7,900,000	1,600,000
Reclassification from accrued taxes to other current liabilities	'	'	'	'	500,000
Alabama Gas Corporation	'	'	'	'	'
Assets of Disposal Group, Including Discontinued Operation [Abstract]	'	'	'	'	'
Cash	11,807,000	'	11,807,000	'	3,032,000
Accounts receivable	50,285,000	'	50,285,000	'	103,748,000
Inventories	39,950,000	'	39,950,000	'	41,200,000
Oil and gas properties	'	'	'	'	0
Less accumulated depreciation, depletion and amortization	-624,704,000	'	-624,704,000	'	0
Utility plant	1,517,534,000	'	1,517,534,000	'	1,491,433,000
Less accumulated depreciation	'	'	'	'	-605,924,000
Other property, net	40,000	'	40,000	'	41,000
Other current assets	16,462,000	'	16,462,000	'	29,458,000
Other long-term assets	142,672,000	'	142,672,000	'	128,780,000
Total assets held for sale	1,154,046,000	'	1,154,046,000	'	1,191,768,000
Total assets held for sale	'	'	'	'	'
Accounts payable	-38,646,000	'	-38,646,000	'	-48,653,000
Royalty payable	0	'	0	'	0
Accrued taxes	-29,337,000	'	-29,337,000	'	-28,027,000
Long-term debt due within one year	-50,000,000	'	-50,000,000	'	'
Notes payable to banks	'	'	'	'	-50,000,000
Other current liabilities	-108,633,000	'	-108,633,000	'	-105,013,000
Other long-term liabilities	-335,369,000	'	-335,369,000	'	-331,409,000
Long-term debt	-199,830,000	'	-199,830,000	'	-249,923,000
Total liabilities held for sale	-761,815,000	'	-761,815,000	'	-813,025,000
Total net assets held for sale	392,231,000	'	392,231,000	'	378,743,000
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]	'	'	'	'	'
Total Income (Loss) From Discontinued Operations	-4,896,000	-1,808,000	34,949,000	44,467,000	'
Black Warrior Basin	'	'	'	'	'
Assets of Disposal Group, Including Discontinued Operation [Abstract]	'	'	'	'	'
Cash	0	'	0	'	0
Accounts receivable	0	'	0	'	2,829,000
Inventories	0	'	0	'	0
Oil and gas properties	'	'	'	'	0
Less accumulated depreciation, depletion and amortization	0	'	0	'	'
Utility plant	0	'	0	'	0
Less accumulated depreciation	'	'	'	'	0
Other property, net	0	'	0	'	0
Other current assets	0	'	0	'	0
Other long-term assets	0	'	0	'	0
Total assets held for sale	0	'	0	'	2,829,000
Total assets held for sale	'	'	'	'	'
Accounts payable	-2,172,000	'	-2,172,000	'	-1,732,000
Royalty payable	0	'	0	'	-550,000
Accrued taxes	0	'	0	'	0
Long-term debt due within one year	0	'	0	'	'
Notes payable to banks	'	'	'	'	0
Other current liabilities	0	'	0	'	-379,000
Other long-term liabilities	0	'	0	'	0
Long-term debt	0	'	0	'	0
Total liabilities held for sale	-2,172,000	'	-2,172,000	'	-2,661,000
Total net assets held for sale	-2,172,000	'	-2,172,000	'	168,000
North Louisiana/East Texas	'	'	'	'	'
Assets of Disposal Group, Including Discontinued Operation [Abstract]	'	'	'	'	'
Cash	0	'	0	'	0
Accounts receivable	0	'	0	'	1,272,000
Inventories	0	'	0	'	68,000
Oil and gas properties	'	'	'	'	348,379,000
Less accumulated depreciation, depletion and amortization	0	'	0	'	-301,609,000
Utility plant	0	'	0	'	0
Less accumulated depreciation	'	'	'	'	0
Other property, net	0	'	0	'	165,000
Other current assets	0	'	0	'	0
Other long-term assets	0	'	0	'	0
Total assets held for sale	0	'	0	'	48,275,000
Total assets held for sale	'	'	'	'	'
Accounts payable	-1,856,000	'	-1,856,000	'	-11,000
Royalty payable	-1,284,000	'	-1,284,000	'	-869,000
Accrued taxes	0	'	0	'	0
Long-term debt due within one year	0	'	0	'	'
Notes payable to banks	'	'	'	'	0
Other current liabilities	-2,000	'	-2,000	'	-21,000
Other long-term liabilities	-2,000	'	-2,000	'	-14,983,000
Long-term debt	0	'	0	'	0
Total liabilities held for sale	-3,144,000	'	-3,144,000	'	-15,884,000
Total net assets held for sale	($3,144,000)	'	($3,144,000)	'	$32,391,000

Dispositions_of_Properties_Nar

Dispositions of Properties Narrative (Details) (Alabama Gas Corporation, USD $)	6 Months Ended		1 Months Ended	3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Aug. 31, 2013	Jun. 30, 2014	Jun. 30, 2014
			Birmingham Metro Operations Center	Birmingham Metro Operations Center	Tuscaloosa
Gas and Oil Acreage [Line Items]	'	'	'	'	'
Gain on sale of assets	$703,000	$0	$10,900,000	'	$700,000
Sale price of property	'	'	'	$13,800,000	'
Lease back period after sale	'	'	'	'20 months	'