Subsequent Events (Details) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended
	Oct. 31, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Subsequent Event [Line Items]
Sale Price of Oil and Gas Property and Equipment		$ 248,500,000
Payments to Acquire Oil and Gas Property	73,200,000
Proceeds from sales of oil and gas properties, net	209,700,000		20,753,000	207,250,000
Potential Post-Close Proceeds From Sale Of Oil And Gas Properties	23,800,000
Fair Value Of Derivative Assets Entered Into On Behalf Of Buyer		500,000	500,000
Barnett Transaction [Member]
Subsequent Event [Line Items]
Sale Price of Oil and Gas Property and Equipment		218,000,000
East Texas Transaction [Member]
Subsequent Event [Line Items]
Sale Price of Oil and Gas Property and Equipment		$ 8,700,000