Employee Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pensions
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 760	$ 598	$ 106
Interest cost	588	455	137
Expected return on plan assets	(733)	(593)	(198)
Amortization of prior service cost	2	1	2
Amortization of actuarial loss	162	127	68
Amortization of transition obligation	2	1	(1)
Settlement loss	508	479	0
Other	0	0	0
Net periodic benefit cost	1,289	1,068	114
Other post-retirement benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost	503	448	621
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of actuarial loss	200	202	330
Amortization of transition obligation	0	0	0
Settlement loss	0	0	0
Other	0	0	(1)
Net periodic benefit cost	$ 703	$ 650	$ 950