Fair Value Measurements (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Net valuation of the Company's derivatives subject to fair value measurement on a recurring basis
Estimated fair value of the Notes	$ 160,900,000	$ 155,300,000
Book value of notes	150,000,000	150,000,000
Quoted Prices in Active Markets (Level 1) [Member]
Net valuation of the Company's derivatives subject to fair value measurement on a recurring basis
Commodity Derivatives:	0	0
Significant Other Observable Inputes (Level 2) [Member]
Net valuation of the Company's derivatives subject to fair value measurement on a recurring basis
Commodity Derivatives:	(4,058,000)	597,000
Significant Unobservable Inputs (Level 3) [Member]
Net valuation of the Company's derivatives subject to fair value measurement on a recurring basis
Commodity Derivatives:	$ 0	$ 0