Long-Term Debt (Details) (USD $)	3 Months Ended		1 Months Ended				1 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Jan. 31, 2012 Term Loan maturing in 2016	Mar. 31, 2012 Term Loan maturing in 2016	Mar. 31, 2012 Term Loan maturing in 2016 Minimum	Mar. 31, 2012 Term Loan maturing in 2016 Maximum	Jan. 31, 2012 7 3/8% senior notes, due 2012	Mar. 31, 2012 7 3/8% senior notes, due 2012
Long Term Debt
Additional borrowings			$ 275,000,000
Quarterly principal payment as a percent of the original principal amount					1.25%	3.75%
Unpaid principal balance payment				158,000,000
Note stated interest rate (as a percent)							7.375%
Repayments of Debt	283,448,000	7,325,000					279,700,000
Expenses recorded related to tender premium, unamortized debt issuance cost write-off, and tender expenses								$ 13,900,000