Defined Benefit Pension Plans - Schedule of Net Periodic Pension Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan [Abstract]
Service cost	$ 4,034	$ 3,968	$ 3,472
Interest cost	2,324	2,264	2,573
Expected return on plan assets	(670)	(594)	(540)
Amortization of prior service costs	61	62	58
Amortization of actuarial net loss	1,533	2,308	1,351
Settlement	1	(2)	1,343
Curtailment	1	(586)	0
Other	0	0	(3)
Net periodic benefit cost	$ 7,284	$ 7,420	$ 8,254