Discontinued Operations Narrative (Details) (USD $)	0 Months Ended		0 Months Ended			3 Months Ended					1 Months Ended
	Sep. 02, 2014 Syndicated Credit Facility Credit Facility, September 2, 2014	Sep. 02, 2014 Syndicated Credit Facility Credit Facility, September 2, 2014	Oct. 30, 2012 Syndicated Credit Facility Credit Facility, October 30, 2012	Aug. 31, 2014 Alabama Gas Corporation	Aug. 31, 2014 Alabama Gas Corporation	Mar. 31, 2014 North Louisiana and East Texas Natural Gas and Oil Properties	Dec. 31, 2013 North Louisiana and East Texas Natural Gas and Oil Properties	Sep. 30, 2013 North Louisiana and East Texas Natural Gas and Oil Properties	Dec. 31, 2013 North Louisiana and East Texas Natural Gas and Oil Properties Natural Gas Mcf	Dec. 31, 2013 North Louisiana and East Texas Natural Gas and Oil Properties Oil MBbls	Oct. 31, 2013 Black Warrior Basin Properties Alabama	Dec. 31, 2012 Black Warrior Basin Properties Alabama Natural Gas Mcf
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of consideration received					$ 1,600,000,000
Amount of debt assumed				267,000,000
Proceeds from sale				1,320,000,000
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
Maximum borrowing capacity		$ 1,500,000,000	$ 1,250,000,000.00
Debt Instrument, Term	5 years		5 years