Basis of Presentation Basis of Presentation - PPE (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts	$ 100,000	$ 1,000,000
Proceeds from Sale of Oil and Gas Property and Equipment	837,000	14,000,000	35,000,000
Accrued incentive compensation costs	5,700,000	7,000,000
Other receivable	$ 17,742,000	$ 15,860,000
Gas gathering system [Member]
Property, Plant and Equipment [Line Items]
Useful life	14 years
Well equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life	3 years
Well equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life	8 years
OKLAHOMA | Building [Member]
Property, Plant and Equipment [Line Items]
Useful life	39 years
State and Local Jurisdiction [Member] | OKLAHOMA
Property, Plant and Equipment [Line Items]
Receivable period for severance tax receivable	2 years 6 months