Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined benefit plans:
Multiemployer pension plans	$ 501	$ 485
Defined contribution pension plans	2,835	2,560
Pension Plan | U.S. Plans
Defined benefit plans:
Service cost	10	11
Interest cost	2,391	2,469
Expected return on plan assets	(3,017)	(2,621)
Recognized prior service costs	0	8
Recognized loss	1,302	1,425
Settlement/curtailment losses	166	0
Defined benefit pension plans net periodic pension cost (income)	852	1,292
Defined benefit pension plan	1,284	471
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	8,600
Pension Plan | International Plans
Defined benefit plans:
Service cost	386	411
Interest cost	5,672	5,734
Expected return on plan assets	(11,145)	(10,424)
Recognized prior service costs	(39)	45
Recognized loss	3,840	4,042
Settlement/curtailment losses	0	0
Defined benefit pension plans net periodic pension cost (income)	(1,286)	(192)
Defined benefit pension plan	9,734	$ 8,337
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	$ 10,200