Financial Instruments (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Notional value of forward currency and option contracts	$ 233,800,000	$ 182,700,000
Line of credit facility, borrowing capacity	600,000,000
Line of credit facility, expiration date	October 2016
Line of credit facility, years	5
Line of credit facility, terminated, borrowing capacity	400,000,000
Line of credit facility, terminated, years	5
Line of credit facility, terminated, expiration date	June 2012
Outstanding borrowings		80,500,000
Accounts receivable collections delayed due to national healthcare system in Greece	13,900,000	32,800,000
Greek bonds received in settlement of accounts receivable	16,800,000
Other (income) expense, net, related to settlement of bonds	7,000,000
Maximum [Member]
Non-interest bearing bonds, maturity in years	three
Minimum [Member]
Non-interest bearing bonds, maturity in years	one
Fair Value, Inputs, Level 2 [Member]
Fair value of long-term debt	997,900,000	937,700,000
Interest Rate Swap Contract [Member]
Notional value of interest rate swap contract	$ 250,000,000
Fixed-rate notes interest percentage	2.875%
Fixed rate notes due date	2016