Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate percentage	36.30%		36.80%	35.80%	36.80%
Deferred income tax (benefit) provision	$ (89,350)		$ 9,095	$ (115,740)	$ 17,356
Changes in Future Income Tax Expense Estimates on Future Cash Flows Related to Proved Oil and Gas Reserves	$ 82,700	$ 24,300		$ 107,000