Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net periodic benefit cost [Abstract]
Total amount amortized out of accumulated other comprehensive income	$ 3,701	$ 5,775	$ 7,392	$ 11,563
Defined contribution plan expense	8,349	8,005	18,157	17,011
U.S. Pension Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	3,479	3,916	6,957	7,831
Interest cost	5,761	5,791	11,523	11,582
Expected return on plan assets	(9,699)	(10,393)	(19,397)	(20,786)
Prior service cost (income)	183	224	366	448
Recognized actuarial (gain) loss	1,610	3,155	3,219	6,310
Transition obligation	0	0	0	0
Other	0	0		810
Net periodic benefit cost	1,334	2,693	2,668	6,195
Foreign Pension Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	1,405	1,663	2,778	3,351
Interest cost	1,394	1,476	2,769	2,962
Expected return on plan assets	(1,974)	(2,011)	(3,922)	(4,030)
Prior service cost (income)	(100)	22	(199)	45
Recognized actuarial (gain) loss	675	661	1,340	1,336
Transition obligation	1	9	2	18
Other	0	1		3
Net periodic benefit cost	1,401	1,821	2,768	3,685
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	739	935	1,479	1,870
Interest cost	1,317	1,265	2,634	2,531
Prior service cost (income)	1,566	1,732	3,133	3,464
Recognized actuarial (gain) loss	(140)	72	(280)	143
Net periodic benefit cost	3,482	4,004	6,966	8,008
Post-Retirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	13	40	26	81
Interest cost	104	128	209	256
Prior service cost (income)	(35)	(93)	(71)	(186)
Recognized actuarial (gain) loss	(59)	(7)	(118)	(15)
Net periodic benefit cost	$ 23	$ 68	$ 46	$ 136