Employee Benefits - Components of Net Periodic Benefit Cost Related to U.S Pension Benefits (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
U.S Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 753	$ 887
Interest cost	1,938	1,795
Expected return on plan assets	(2,517)	(2,452)
Amortization of prior service cost	0	1,235
Amortization of net actuarial loss	845	0
Net periodic benefit cost	1,019	1,465
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	389	651
Interest cost	533	541
Expected return on plan assets	(633)	(700)
Amortization of prior service cost	9	3
Amortization of net actuarial loss	106	168
Net periodic benefit cost	$ 404	$ 663