Retirement Plans (Details) - Narrative (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Expense recognized on defined contribution plans	$ 53,600,000	$ 42,400,000	$ 37,800,000
Defined contribution plans, vesting period	5 years
US Plan
Defined Benefit Plan Disclosure [Line Items]
Number of years of compensation for calculating benefit	3
Number of years of employment considered at retirement	10 years
Fair value of plan assets	29,800,000	25,900,000
Accrued pension liability	3,300,000	3,300,000
Number of mutual funds held by plan	2
Europe plans
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liability	18,500,000	14,600,000
Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	39,313,000	34,955,000	33,294,000
Accrued pension liability	43,770,000	37,312,000
Projected benefit obligation	$ 83,083,000	$ 72,267,000	$ 66,327,000