Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net periodic benefit cost [Abstract]
Total amount amortized out of accumulated other comprehensive income	$ 3,021	$ 3,701	$ 6,022	$ 7,392
Defined contribution plan expense	10,839	8,349	22,197	18,157
U.S. Pension Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	3,021	3,479	6,042	6,957
Interest cost	5,430	5,761	10,859	11,523
Expected return on plan assets	(9,953)	(9,699)	(19,906)	(19,397)
Prior service cost (credit)	106	183	213	366
Recognized actuarial gain	1,395	1,610	2,791	3,219
Transition obligation	0	0	0	0
Net periodic expense	(1)	1,334	(1)	2,668
Foreign Pension Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	1,343	1,405	2,660	2,778
Interest cost	1,285	1,394	2,549	2,769
Expected return on plan assets	(1,833)	(1,974)	(3,637)	(3,922)
Prior service cost (credit)	(112)	(100)	(222)	(199)
Recognized actuarial gain	864	675	1,705	1,340
Transition obligation	1	1	2	2
Net periodic expense	1,548	1,401	3,057	2,768
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	618	739	1,236	1,479
Interest cost	1,019	1,317	2,038	2,634
Prior service cost (credit)	1,103	1,566	2,205	3,133
Recognized actuarial gain	(298)	(140)	(596)	(280)
Net periodic expense	2,442	3,482	4,883	6,966
Post-Retirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	9	13	17	26
Interest cost	73	104	146	209
Prior service cost (credit)	2	(35)	4	(71)
Recognized actuarial gain	(40)	(59)	(80)	(118)
Net periodic expense	$ 44	$ 23	$ 87	$ 46