Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined benefit plans:
Multiemployer pension plans	$ 492	$ 498	$ 1,512	$ 1,481
Defined contribution pension plans	2,306	3,278	7,888	8,306
Pension Plan | U.S. Plans
Defined benefit plans:
Service cost	10	10	31	32
Interest cost	2,391	2,469	7,172	7,408
Expected return on plan assets	(3,017)	(2,620)	(9,051)	(7,863)
Recognized prior service costs	0	8	0	24
Recognized loss	1,302	1,425	3,906	4,276
Settlement/curtailment losses			166	0
Defined benefit pension plans net periodic pension cost (benefit)	686	1,292	2,224	3,877
Defined benefit pension plan	5,958	4,112	9,309	5,054
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	500		500
Pension Plan | International Plans
Defined benefit plans:
Service cost	401	426	1,195	1,243
Interest cost	5,498	5,843	16,612	17,349
Expected return on plan assets	(10,820)	(10,632)	(32,661)	(31,571)
Recognized prior service costs	(37)	48	(113)	139
Recognized loss	3,737	4,130	11,267	12,260
Settlement/curtailment losses			0	0
Defined benefit pension plans net periodic pension cost (benefit)	(1,221)	(185)	(3,700)	(580)
Defined benefit pension plan	3,219	$ 3,038	16,192	$ 14,338
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	$ 2,400		$ 2,400