Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Pension and postretirement benefits [Abstract]
Amortization of net actuarial loss, gross amount	[1]	$ 995	$ 110
Amortization of net actuarial loss, income tax provision	[1]	(250)	(28)
Amortization of net actuarial loss, net amount	[1]	745	82
Foreign currency translation, gross amount		(497)	(1,274)
Foreign currency translation, income tax provision		0	0
Foreign currency translation, net amount		(497)	(1,274)
Total other comprehensive income, gross amount		498	(1,164)
Total other comprehensive income, income tax provision		(250)	(28)
Total other comprehensive income (loss), net of taxes		$ 248	$ (1,192)

[1] Actuarial gains/(losses) are amortized into other income (expense). (See Note 11, Retirement Plans)