Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
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			$ 2,700	$ 2,200
Pension Benefits
Components of net periodic benefit cost:
Service cost	2,036	2,103	6,131	6,318
Interest cost	6,005	5,117	18,057	15,431
Expected return on plan assets	(7,117)	(6,071)	(21,372)	(18,346)
Amortization of transition obligation	(25)	(27)	(74)	(81)
Amortization of prior service cost	673	485	2,019	1,465
Amortization of net actuarial losses	4,010	5,901	12,045	17,703
Net pension expense	5,582	7,508	16,806	22,490
U.S. plans, Pension Benefits
Components of net periodic benefit cost:
Estimated cash contribution to the Plans in 2014 based on current actuarial calculations			20,000
Employer contributions	11,200		15,200
Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost	28	40	83	120
Interest cost	123	127	368	382
Amortization of net actuarial losses	104	193	314	578
Net pension expense	$ 255	$ 360	$ 765	$ 1,080