Pension and Postretirement Benefits - Components of Net Periodic Benefit Cost of Pension and Postretirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
UNITED STATES | Pension Plans
Net periodic benefit cost:
Service cost		$ 15
Interest cost	$ 160	214
Expected return on plan assets	(1)	(34)
Recognized net actuarial loss	135	106
Net periodic benefit cost	294	301
UNITED STATES | Postretirement Benefit Plans
Net periodic benefit cost:
Service cost	15	20
Interest cost	88	124
Amortization of prior service credit	(36)	(47)
Recognized net actuarial loss	82	77
Net periodic benefit cost	149	174
Foreign Pension Plans
Net periodic benefit cost:
Service cost	110	101
Interest cost	84	94
Expected return on plan assets	(131)	(122)
Recognized net actuarial loss	46	38
Net periodic benefit cost	$ 109	$ 111