CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 28,655	$ 14,520	$ 59,873	$ 27,779
Foreign currency translation adjustment	2,758	5,629	(10,501)	(1,265)
Pension and other postretirement benefits:
Pension settlement benefits, net of tax (Note 4)	0	(48)	0	(48)
Actuarial net gain incurred, net of tax (Note 4)	0	626	0	626
Amortization of loss, net of tax (Note 4)	58	67	121	133
Derivative instrument designated as cash flow hedge:
Change in unrealized gain (loss) before reclassifications, net of tax (Note 4)	0	383	0	(866)
Unrealized gain reclassified into earnings, net of tax (Note 4)	0	(267)	0	(334)
Other comprehensive income (loss)	2,816	6,390	(10,380)	(1,754)
Comprehensive income	$ 31,471	$ 20,910	$ 49,493	$ 26,025