Disclosure About Oil and Gas Producing Activities (Unaudited) (Details 5) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Results of Operations, Oil and Gas Producing Activities Net Income (Excluding Corporate Overhead and Interest Costs) [Abstract]
Oil and gas revenue	$ 839,111	$ 1,230,020	$ 933,404
Production expenses	(288,231)	(280,631)	(212,578)
Depletion and depreciation expense	(401,200)	(292,951)	(243,390)
Write-downs of proved oil and gas properties	(3,144,899)	0	0
Income taxes	(9,841)	3,736	(2,821)
Total	$ (3,005,060)	$ 660,174	$ 474,615