Debt Debt (Details) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended													12 Months Ended						12 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 25, 2011 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25%	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25%	Dec. 31, 2011 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25%	Oct. 08, 2010 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25%	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25% First Step Down	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25% First Step Down Minimum	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25% First Step Down Maximum	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25% Second Step Down	Dec. 31, 2012 Senior Secured Credit Facility, due Oct 2017, variable rate 4.25% Second Step Down Maximum	Dec. 31, 2012 Senior Notes, due Oct 2018, fixed rate 9.5%	Dec. 31, 2011 Senior Notes, due Oct 2018, fixed rate 9.5%	Oct. 19, 2010 Senior Notes, due Oct 2018, fixed rate 9.5%	Dec. 31, 2012 Senior Secured Revolving Credit Facility	Oct. 08, 2010 Senior Secured Revolving Credit Facility	Dec. 31, 2012 Amended Senior Secured Revolving Credit Facility	Dec. 31, 2011 Amended Senior Secured Revolving Credit Facility	Feb. 25, 2011 Amended Senior Secured Revolving Credit Facility	Oct. 08, 2010 Amended Senior Secured Revolving Credit Facility	Dec. 31, 2012 Other Assets	Dec. 31, 2011 Other Assets	Dec. 31, 2012 October 2010 Refinancing	Oct. 08, 2010 October 2010 Refinancing	Dec. 31, 2012 October 2010 Refinancing Senior Secured Revolving Credit Facility
Debt Instrument [Line Items]
Senior secured credit facility due					$ 472,000,000	$ 682,500,000
Senior notes due													760,800,000	765,800,000
Discount	(23,300,000)	(29,400,000)																			(7,400,000)				(29,600,000)
Total debt	1,209,500,000	1,418,900,000
Less current maturities	(7,420,000)	(7,420,000)
Long-term debt, less current maturities	1,202,063,000	1,411,448,000
Debt Instruments (Narrative) [Abstract]
Face amount of debt							900,000,000								825,000,000		50,000,000
Line of Credit Facility, Maximum Borrowing Capacity							250,000,000									150,000,000	50,000,000			75,000,000
LIBOR Rate Floor																		2.25%						1.50%		2.50%
Debt Instrument, Basis Spread on Variable Rate																								4.50%
Base Rate Floor																		1.25%						2.50%		1.50%
Federal Funds Rate Additional Margin																								0.50%
One Month LIBOR Rate Floor																								1.50%
One Month LIBOR Rate Additional Margin																								1.00%
One Month LIBOR Rate Additional Margin Uplift																								3.50%
Upfront Fee on Debt, Percent																								1.00%
LIBOR Rate Additional Margin																		3.00%								4.50%
Payments of Debt Restructuring Costs																			12,300,000
Payments of Debt Restructuring Costs, Recorded as Additional Discount on Debt																			7,400,000
Payments of Debt Restructuring Costs, Recorded as Deferred Financing Costs																			800,000
Debt modification costs	0	4,031,000	0																4,031,000
Proceeds from Lines of Credit				742,000,000
Line of Credit Facility, Current Borrowing Capacity																		12,100,000
Mandatory Prepayment of Debt, Percent per Quarter					0.25%
Mandatory Prepayment of Debt, Percent per Annum					1.00%
Percent of Excess Cash Flow Required For Mandatory Prepayment, Annual Mininum					50.00%
Percent of Proceeds From Asset Sales and Insurance Proceeds Subject to Mandatory Prepayment					100.00%
Percent of Excess Cash Flow Required Applied as a Prepayment								25.00%			0.00%
Consolidated Leverage Ratio Triggering Excess Cash Flow Required Payment Corresponding to Step Down									300.00%	450.00%		300.00%
Effective interest rate on debt	7.80%												10.90%
Payment of debt issuance costs	0	12,295,000	57,602,000
Deferred Finance Costs, Net													$ 28,200,000			$ 800,000						$ 16,800,000	$ 21,700,000