Debt, Total (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Debt Disclosure [Abstract]
Revolving Credit Facility	$ 0	$ 50,000,000
5.875% Senior Notes due 2020	350,000,000	0
Capital lease obligations	4,032,000	0
Total Debt	354,032,000	50,000,000
Less: Current maturities	110,000	0
Debt, less current maturities	353,922,000	50,000,000
Aggregate maturities of debt due in 2013	100,000
Aggregate maturities of debt due in 2014	200,000
Aggregate maturities of debt due in 2015	100,000
Aggregate maturities of debt due in 2016	200,000
Aggregate maturities of debt due in 2017	$ 200,000

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Amount borrowed under the credit facility as of the balance sheet date.

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