Indebtedness (Narrative) (Details)			3 Months Ended																3 Months Ended
	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Mar. 31, 2013 1 1/4% Convertible Senior Subordinated Notes Due December 15, 2036 [Member] USD ($)	Mar. 31, 2012 1 1/4% Convertible Senior Subordinated Notes Due December 15, 2036 [Member] USD ($)	Dec. 31, 2012 1 1/4% Convertible Senior Subordinated Notes Due December 15, 2036 [Member] USD ($)	Mar. 31, 2013 4 1/2% Senior Unsecured Term Loan Due May 2, 2016 [Member] USD ($)	Mar. 31, 2013 4 1/2% Senior Unsecured Term Loan Due May 2, 2016 [Member] EUR (€)	Dec. 31, 2012 4 1/2% Senior Unsecured Term Loan Due May 2, 2016 [Member] USD ($)	Mar. 31, 2013 5 7/8% Senior Notes due 2021 [Member] USD ($)	Dec. 31, 2012 5 7/8% Senior Notes due 2021 [Member] USD ($)	Mar. 31, 2013 5 7/8% Senior Notes due 2021 [Member] Interest Accrual, Option Two [Member]	Mar. 31, 2013 Revolving Credit Facility [Member] USD ($)	Mar. 31, 2013 Credit Facility [Domain] Interest Accrual, Option Two [Member]	Mar. 31, 2013 Credit Facility [Domain] Interest Accrual, Option Three [Member]	Mar. 31, 2013 Credit Facility [Domain] Minimum [Member] Interest Accrual, Option One [Member]	Mar. 31, 2013 Credit Facility [Domain] Minimum [Member] Interest Accrual, Option Three [Member] Variable Basis, Additional Margin [Member]	Mar. 31, 2013 Credit Facility [Domain] Maximum [Member] Interest Accrual, Option One [Member]	Mar. 31, 2013 Credit Facility [Domain] Maximum [Member] Interest Accrual, Option Three [Member] Variable Basis, Additional Margin [Member]	Mar. 31, 2013 Term Loan Facility [Member] USD ($)	Mar. 31, 2013 Term Loan Facility [Member] Future Periodic Payment [Member] USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount	$ 201,300,000	$ 201,300,000
Interest expense on the liability component of convertible debt			2,900,000	2,800,000
Effective interest rate			6.10%	6.10%
Debt instrument, discount amortization period			December 2013
Debt maturity date			Dec. 15, 2036
Convertible senior subordinated notes conversion price			$ 40.65
Convertible senior subordinated notes, conversion rate			24.5975
Convertible senior subordinated notes, principal amount			1,000
Convertible senior subordinated notes, triggering event, percent of closing sales price to conversion price			120.00%
Debt Instrument, Unamortized Discount	6,900,000	9,200,000
Senior Notes						256,400,000	200,000,000.0	264,200,000	300,000,000	300,000,000
Days within trading period required to trigger qualifying event			20 days
Trading period in which qualifying event must occur			30 days
Maximum borrowing capacity on line of credit facility												600,000,000							375,000,000
Periodic payment required on term loan																			5,000,000	10,000,000
Margin on variable rate											0.50%		0.50%	1.00%	1.00%	0.00%	2.00%	0.50%
Long-term debt, less current portion	1,155,100,000	1,035,600,000
Credit facility	591,900,000	465,000,000
Remaining borrowing capacity on line of credit facility	383,100,000	515,000,000
Long-term debt, estimated fair value			260,900,000		250,600,000				326,100,000	327,200,000
Convertible Debt	194,400,000	192,100,000
Outstanding letters of credit	$ 16,700,000	$ 15,800,000