Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Net valuation of the Company's derivatives subject to fair value measurement on a recurring basis
Estimated fair value of the Notes	$ 327,000	$ 301,000
Book value of notes	350,000	350,000
Quoted Prices in Active Markets (Level 1)
Derivatives, Fair Value [Line Items]
Commodity derivatives at fair value	0	0
Significant Other Observable Inputs (Level 2)
Derivatives, Fair Value [Line Items]
Commodity derivatives at fair value	5,675	8,631
Significant Unobservable Inputs (Level 3)
Derivatives, Fair Value [Line Items]
Commodity derivatives at fair value	$ 0	$ 0