Fair Value Measurements Fair Value of Debt (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 1,648,961,000	$ 1,703,120,000
Carrying Value	1,650,877,000	1,545,000,000
Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	1,276,527,000	1,045,000,000
Convertible Senior Subordinated Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	56,350,000	250,000,000
Term Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	318,000,000	250,000,000
Fair Value, Inputs, Level 1 [Member] | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,262,938,000	1,061,945,000
Fair Value, Inputs, Level 1 [Member] | Convertible Senior Subordinated Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	83,325,000	371,975,000
Fair Value, Inputs, Level 2 [Member] | Term Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 302,698,000	$ 269,200,000