Basis of Presentation Basis of Presentation - Additional Information (Details) (USD $) Share data in Millions, unless otherwise specified			0 Months Ended				0 Months Ended
	Mar. 31, 2013 10.375% Senior Unsecured Notes due 2016	Dec. 31, 2012 10.375% Senior Unsecured Notes due 2016	May 06, 2013 Subsequent Event Senior Notes	Apr. 25, 2013 Subsequent Event Senior Notes 10.375% Senior Unsecured Notes due 2016	May 06, 2013 Subsequent Event Senior Notes 10.375% Senior Unsecured Notes due 2016	Apr. 11, 2013 Subsequent Event Senior Notes 10.375% Senior Unsecured Notes due 2016	Apr. 24, 2013 Subsequent Event Senior Notes 8.5% Senior Notes due 2020	Apr. 24, 2013 Eagle Ford Shale, Gonzalez and Lavaca Counties Subsequent Event acre Boe Well
Oil and Gas Property [Abstract]
Sales price								$ 400,000,000
Payments to acquire oil and gas properties								360,000,000
Stock issued for oil and gas property acquisition								10
Gross mineral acres acquired								40,600
Net mineral acres acquired								19,000
Gross working interest acquired								46
Net working interests acquired								22.1
Proved developed reserves								12,000,000
Percentage of reserves that are gas and NGLs								96.00%
Gas reserves proved								37.00%
Debt Instruments [Abstract]
Principal amount	300,000,000	300,000,000				300,000,000
Annual interest rate		10.375%				10.375%	8.50%
Percentage that tendered						58.00%
Consideration payable per $1,000 of principal					1,061	1,065
Consent payment per $1,000 of principal						30.00
Early repayment of senior notes				191,000,000
Interest portion of early repayment of senior notes				6,500,000
Percentage that were redeemed					42.00%
Loss on extinguishment of debt			29,000,000
Proceeds from senior notes							775,000,000
Proceeds from senior notes used for acquisition							$ 380,000,000