Organization and Basis of Presentation (Sale of Alabama Gas Corporation) (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 02, 2014	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax gain on disposal of discontinued operations		$ 724,594	$ 5,605
Alabama Gas Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration	$ 1,600,000
Debt assumed	267,000
Proceeds from sale	1,320,000
Pre-tax gain on disposal of discontinued operations	$ 726,500