Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Components of net periodic benefit cost:
Contributions to U.S defined contribution plans by the Company, maximum percentage of eligible compensation			5.00%
Matching contributions to U.S defined contribution plans by the Company			$ 2,200	$ 2,100
Pension Benefits
Components of net periodic benefit cost:
Service cost	2,103	1,911	6,318	5,795
Interest cost	5,117	5,387	15,431	16,340
Expected return on plan assets	(6,071)	(6,089)	(18,346)	(18,408)
Amortization of transition obligation	(27)	(27)	(81)	(81)
Amortization of prior service cost	485	535	1,465	1,610
Amortization of net actuarial losses	5,901	4,484	17,703	13,592
Net pension expense	7,508	6,201	22,490	18,848
U.S. plans, Pension Benefits
Components of net periodic benefit cost:
Employer contributions	11,000		15,000
Estimated cash contribution to the Plans in 2013 based on current actuarial calculations	21,000		21,000
Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost	40	45	120	134
Interest cost	127	169	382	508
Amortization of transition obligation		16		47
Amortization of net actuarial losses	193	242	578	725
Net pension expense	$ 360	$ 472	$ 1,080	$ 1,414