Retirement Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 plan	Dec. 31, 2010	Dec. 31, 2009
Defined contribution plans
Number of defined contribution retirement plans	6
Cost of defined contribution plans	$ 6.7	$ 6.3	$ 6.1
Contributions to pension funds	$ 1.8	$ 1.7	$ 1.7
Defined contribution plan - U.S Plans
Defined contribution plans
Number of defined contribution retirement plans	2
Defined contribution plan - European and Canadian Plans
Defined contribution plans
Number of defined contribution retirement plans	4
Defined contribution plan - European and Canadian Plans | Minimum
Defined contribution plans
Entity's contribution to retirement plans as percentage of employees' compensation	3.00%
Defined contribution plan - European and Canadian Plans | Maximum
Defined contribution plans
Entity's contribution to retirement plans as percentage of employees' compensation	15.00%