Disclosure About Oil and Gas Producing Activities (Unaudited) (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Results of Operations, Oil and Gas Producing Activities Net Income (Excluding Corporate Overhead and Interest Costs) [Abstract]
Oil and gas revenue	$ 933,404,000	$ 809,974,000	$ 1,101,796,000
Production expenses	(212,578,000)	(184,229,000)	(205,363,000)
Depletion and depreciation expense	(243,390,000)	(388,985,000)	(346,394,000)
Write-downs of proved oil and gas properties	0	(2,972,464,000)	0
Income taxes	(2,821,000)	662,698,000	(197,464,000)
Total	$ 474,615,000	$ (2,073,006,000)	$ 352,575,000