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
Defined benefit plans:
Multiemployer pension plans	$ 498	$ 505	$ 983	$ 1,026
Defined contribution pension plans	2,468	2,476	5,028	5,302
U. S. Plans
Defined benefit plans:
Service cost	942	946	1,884	1,892
Interest cost	2,470	2,545	4,939	5,090
Expected return on plan assets	(3,552)	(3,601)	(7,104)	(7,202)
Recognized prior service costs	8	15	16	31
Recognized loss	1,425	1,372	2,850	2,744
Defined benefit pension plans net periodic pension cost (income)	1,293	1,277	2,585	2,555
Defined benefit pension plan	471	470	942	940
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year			5,300
International Plans
Defined benefit plans:
Service cost	406	405	817	809
Interest cost	5,773	6,984	11,507	14,107
Expected return on plan assets	(10,515)	(11,219)	(20,939)	(22,682)
Recognized prior service costs	46	45	91	89
Recognized loss	4,087	3,142	8,129	6,360
Defined benefit pension plans net periodic pension cost (income)	(203)	(643)	(395)	(1,317)
Defined benefit pension plan	$ 2,963	$ 3,254	11,300	$ 13,052
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year			$ 6,200