Commitments and Contingencies (Details) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss Contingencies [Line Items]
Estimated litigation liability accrued				$ 2,250,000
Loss Contingency, Loss in Period			1,400,000
Litigation settlement expense	800,000
Gain related to litigation settlement	9,000,000	0	0	12,400,000
Non-cash gain related to litigation settlement	4,200,000	0	0	4,164,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2013		1,211,000
2014		1,032,000
2015		1,026,000
2016		988,000
2017		898,000
Thereafter		0
Total		5,155,000
Operating leases rent expense		$ 1,391,000	$ 1,342,000	$ 1,090,000
Natural Gas [Member] | OKLAHOMA
Loss Contingencies [Line Items]
Amount of natural gas commited under firm transportation agreement		7,600