Consolidated Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
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