Debt (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 2,475,228,000		$ 2,475,228,000		$ 2,381,929,000
Debt instrument stated interest rate (in hundredths)	7.75%		7.75%
Amortization of Financing Costs	1,300,000	1,500,000	4,300,000
Letters of Credit Outstanding, Amount	11,000,000		11,000,000
Interest rate swap agreements	(49,428,000)		(49,428,000)		(35,473,000)
Current portion of debt	(26,685,000)		(26,685,000)		(26,447,000)
Long-term debt, net	2,029,742,000		2,029,742,000		1,968,274,000
Weighted average spread on interest rate swap agreements (in hundredths)	4.90%		4.90%
Total debt redemption costs		20,200,000	4,000,000	21,200,000
Proceeds from Issuance of Long-term Debt			425,000,000	600,000,000
Debt related costs	0	0	35,092,000	0
Current Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0		0		0
Deferred Finance Costs, Net	2,000,000		2,000,000
Revolving credit facility borrowing capacity	300,000,000		300,000,000
Applicable margin with respect to the floating base rate loans	0.75%		0.75%
London interbank offered rate (LIBOR) plus an applicable margin	0.0175
Write Off Of Deferred Debt Issuance Cost	8,300,000
Senior Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	425,000,000		425,000,000		444,375,000
Debt instrument stated interest rate (in hundredths)	4.00%		4.00%
7.75% Senior Subordinated Notes, Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	550,000,000		550,000,000		550,000,000
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	318,054,000		318,054,000		575,000,000
Extinguishment of Debt, Amount			256,900,000
4.00% Junior Subordinated Convertible Debentures, due 2033 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	345,000,000		345,000,000		345,000,000
3.25% Convertible Senior Debentures, Due 2035 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	427,500,000		427,500,000		452,500,000
Extinguishment of Debt, Amount			25,000,000
3.75% Convertible Senior Subordinated Notes Due 2042 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	390,000,000		390,000,000		0
Debt instrument stated interest rate (in hundredths)	3.75%		3.75%
Debt Instrument, Convertible, Conversion Price	$ 41.50		$ 41.50
Aggregate principal amount outstanding	390,000,000		390,000,000
Capitalized Lease and Other Debt Obligations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 19,674,000		$ 19,674,000		$ 15,054,000