Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Notes Payable 4.5 Percent Due 2021 [Member]	Dec. 31, 2011 Notes Payable 4.5 Percent Due 2021 [Member]	Dec. 31, 2012 Forward exchange contracts	Dec. 31, 2011 Forward exchange contracts	Dec. 31, 2011 Derivatives designated as hedging instruments Interest-rate swap	Dec. 31, 2012 (Level 2) Measured on a recurring basis Interest-rate swap	Dec. 31, 2011 (Level 2) Measured on a recurring basis Interest-rate swap
Derivative Instruments
Maximum Remaining Maturity of Foreign Currency Derivatives	6 months
Derivative Assets (Liabilities), at Fair Value, Net							$ 17.0	$ 3.3
Notional amounts of derivatives				6.1	9.8	400.0
Number of swap agreements						4
Debt instrument, face amount		$ 400
Fixed-rate (as a percent)			4.50%