Debt (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Credit Agreement
Credit Agreement
Multi-currency borrowing capacity	$ 300.0
Term of senior unsecured revolving credit facility	5 years
Potential additional borrowing capacity	150.0
Sublimit on letters of credit	75.0
Unused and available credit under the credit agreement	270.4
Stand-by letters of credit outstanding	29.6
Eurocurrency rate loans | LIBOR | Minimum
Credit Agreement
Interest rate added to base rate (as a percent)	1.70%
Eurocurrency rate loans | LIBOR | Maximum
Credit Agreement
Interest rate added to base rate (as a percent)	2.30%
Base rate loans and swing line loans | Minimum
Credit Agreement
Interest rate added to base rate (as a percent)	0.70%
Base rate loans and swing line loans | Maximum
Credit Agreement
Interest rate added to base rate (as a percent)	1.30%
Base rate loans and swing line loans | LIBOR
Credit Agreement
Interest rate added to base rate (as a percent)	1.00%
Base rate loans and swing line loans | Federal funds
Credit Agreement
Interest rate added to base rate (as a percent)	0.50%
Unsecured senior notes
Credit Agreement
Repayment of debt	$ 75.0