Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension and postretirement benefits [Abstract]
Amortization of net actuarial loss, Gross Amount	[1]	$ 304	$ (87)	$ 414	$ 463
Amortization of net actuarial loss, Income Tax (Provision) Benefit	[1]	(77)	21	(105)	(118)
Amortization of net actuarial loss, Net Amount	[1]	227	(66)	309	345
Actuarial gains (losses), Gross Amount	[1]	(3,609)	8,167	(3,609)	8,167
Actuarial gains (losses), Income Tax (Provision) Benefit	[1]	905	(2,044)	905	(2,044)
Actuarial gains (losses), Net Amount	[1]	(2,704)	6,123	(2,704)	6,123
Foreign currency translation, Gross Amount		351	(53)	(923)	76
Foreign currency translation, Income Tax (Provision) Benefit		0	0	0	0
Foreign currency translation, Net Amount		351	(53)	(923)	76
Total other comprehensive income, Gross Amount		(2,954)	8,027	(4,118)	8,706
Total other comprehensive income, Income Tax (Provision) Benefit		828	(2,023)	800	(2,162)
Total other comprehensive income (loss), net of taxes		$ (2,126)	$ 6,004	$ (3,318)	$ 6,544

[1] Actuarial gains (losses) are amortized into other income. (See Note 13, Retirement Plans)