Employee Benefit Plans (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 43	$ 102	$ 118
Interest cost	9,878	10,165	12,357
Expected return on plan assets	(10,485)	(10,721)	(14,041)
Recognized prior service costs	33	63	81
Recognized losses	5,701	5,493	4,919
Settlement/curtailment loss (gain)	0	276	0
Defined benefit plans pension cost	5,170	5,378	3,434
Defined contribution plans	4,239	3,833	3,921
Net periodic pension cost, U.S. Plans	$ 10,059	9,847	8,208
U.S. Plans | Maximum
Defined Contribution Plan [Abstract]
Employer matching contribution (as a percent)	4.00%
U.S. Plans | Multiemployer Plans, Pension, Domestic [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Multiemployer plans	$ 650	636	853
International Plans
Defined Contribution Plan [Abstract]
Additional contribution towards insurance and administrative costs (as a percent)	2.00%
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 1,724	1,585	1,648
Interest cost	21,459	26,822	36,282
Expected return on plan assets	(40,469)	(42,979)	(50,091)
Recognized prior service costs	186	189	188
Recognized losses	16,283	12,002	16,875
Settlement/curtailment loss (gain)	(20)	79	(23)
Defined benefit plans pension cost	(837)	(2,302)	4,879
Defined contribution plans	5,905	5,807	6,765
Net periodic pension cost, International Plans	$ 6,374	4,873	13,107
International Plans | Maximum
Defined Contribution Plan [Abstract]
Employer matching contribution (as a percent)	6.00%
International Plans | Multiemployer Plans, Pension, Domestic [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Multiemployer plans	$ 1,306	$ 1,368	$ 1,463