Long-Term Debt (Details) (USD $)	3 Months Ended						3 Months Ended		0 Months Ended				3 Months Ended		1 Months Ended					3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Letter of Credit [Member]	Mar. 31, 2013 Term Loan	Dec. 31, 2012 Term Loan	Mar. 31, 2013 Senior Secured Credit Facility	Dec. 31, 2012 Senior Secured Credit Facility	May 06, 2010 Senior Subordinated Notes Due 2020	Mar. 31, 2013 Senior Subordinated Notes Due 2020	Dec. 31, 2012 Senior Subordinated Notes Due 2020	Dec. 31, 2011 Senior Subordinated Notes Due 2020	Mar. 31, 2013 Senior Subordinated Notes Due 2022	Dec. 31, 2012 Senior Subordinated Notes Due 2022	Aug. 31, 2009 Senior Subordianted Notes Due 2017 [Member]	Mar. 31, 2013 Senior Notes Due 2017 [Member]	Dec. 31, 2012 Senior Notes Due 2017 [Member]	May 06, 2010 Senior Notes Due 2017 [Member]	Aug. 31, 2009 Senior Notes Due 2017 [Member]	Mar. 31, 2013 Senior Subordinated Notes due 2015 [Member]	Mar. 31, 2013 LIBOR Term Loan	Mar. 31, 2013 Base Rate Term Loan	Mar. 31, 2013 Minimum LIBOR Term Loan
Debt Instrument [Line Items]
Long-term Debt	$ 1,440,000,000		$ 1,440,500,000		$ 319,000,000	$ 319,700,000	$ 0	$ 0		$ 350,000,000	$ 350,000,000	$ 350,000,000	$ 325,000,000	$ 325,000,000		$ 446,000,000	$ 445,800,000
Proceeds from issuance of debt									341,500,000				318,000,000		434,000,000
Debt Instrument, Basis Spread on Variable Rate																					3.00%	1.50%	1.00%
Debt Instrument, Face Amount					325,000,000								325,000,000						450,000,000	385,000,000
Debt Instrument, Repayment Amount to Parent Company																				10,000,000
Repayments of Long-term Debt							70,000,000													407,000,000
Long-term Debt, Current Maturities	(3,250,000)		(3,250,000)		(3,250,000)
Long-term debt less current portion	1,436,740,000		1,437,251,000
Interest expense before capitalization of interest	29,200,000	27,400,000
Interest Income, Other	(100,000)	(100,000)
Less: capitalized interest	(400,000)	(5,400,000)
Net interest expense, net of capitalized interest	28,670,000	21,918,000
Long-term Debt Instrument, Repayment, Percent of Face Amount																				103.75%
Debt Instrument, Interest Rate, Stated Percentage									8.75%					7.75%					8.625%	7.50%
Long-term Debt Instrument, Issuance Price, Percent of Face Amount																		98.597%
Line of Credit Facility, Maximum Borrowing Capacity							410,000,000
Letter of Credit, amount outstanding				8,100,000
Loss on early extinguishment of debt	$ 0	$ (20,718,000)																		$ 20,700,000