Long-Term Debt (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Discount	$ (22,500,000)		$ (23,300,000)
Total Long-term Debt	1,209,100,000		1,209,500,000
Less current maturities	(4,720,000)		(7,420,000)
Long-term debt, less current maturities	1,204,422,000		1,202,063,000
Debt Instruments (Narrative) [Abstract]
Debt modification costs	1,296,000	0
Senior Secured Credit Facility, due Oct 2017, variable rate 3.75%
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.75%
Senior secured credit facility due	470,800,000
Senior Secured Credit Facility, due Oct 2017, variable rate 4.25%
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.25%
Senior secured credit facility due			472,000,000
Senior Notes due Oct 2018, at a fixed rate 9.5%
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		9.50%
Senior Notes due October 2018, at a fixed rate of 9.5%	$ 760,800,000		$ 760,800,000