Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Plan	Dec. 31, 2010	Dec. 31, 2009
Change in plan assets:
Employer contributions	$ 22,800	$ 17,300
Pension Benefits
Defined Benefit Plan Disclosure
Number of U.S. defined benefit pension plans	2
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	457,321	429,800
Service cost	7,832	7,542
Interest cost	22,684	23,100	23,276
Plan participants' contributions		26
Plan amendments		5,452
Actuarial (gain) loss	27,642	17,675
Foreign exchange translation	(2,450)	(3,947)
Benefits paid	(24,420)	(22,327)
Projected benefit obligation at end of year	488,609	457,321	429,800
Change in plan assets:
Fair value of plan assets at the beginning of the year	296,530	268,177
Actual return on plan assets	(2,001)	29,878
Employer contributions	22,844	17,267
Plan participants' contributions		26
Foreign exchange translation	(2,131)	636
Benefits paid	(20,188)	(19,454)
Fair value of plan assets at the end of the year	295,054	296,530	268,177
Funded status	(193,555)	(160,791)
Accumulated benefit obligation	469,547	435,618
Components of net periodic benefit cost:
Service cost	7,073	5,907	7,043
Interest cost	22,684	23,100	23,276
Expected return on plan assets	(25,226)	(28,016)	(25,026)
Net amortization of actuarial losses	14,528	17,051	11,238
Net pension expense	19,059	18,042	16,531
International Plans
Change in projected benefit obligation:
Projected benefit obligation at end of year	48,000	51,000
Contribution required to be made during 2012, included in other accrued expenses	3,200
Other Postretirement Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	19,095	14,832
Service cost	198	165
Interest cost	843	786	836
Actuarial (gain) loss	(2,299)	5,315
Benefits paid	(1,139)	(2,003)
Projected benefit obligation at end of year	16,698	19,095	14,832
Components of net periodic benefit cost:
Service cost	198	165	160
Interest cost	843	786	836
Amortization of transition obligation	62	62	62
Net amortization of actuarial losses	1,291	882	773
Net pension expense	$ 2,394	$ 1,895	$ 1,831