CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 7,006	$ 23,387	$ 34,785	$ 76,079
Foreign currency translation adjustment	11,269	(10,187)	10,004	(12,262)
Pension and other postretirement benefits:
Pension settlement benefits, net of tax (Note 4)	0	0	(48)	0
Actuarial net gain incurred, net of tax (Note 4)	3	0	629	0
Amortization of loss, net of tax (Note 4)	66	172	199	485
Derivative instrument designated as cash flow hedge:
Change in unrealized loss before reclassifications, net of tax (Note 4)	(638)	(158)	(1,504)	(1,362)
Unrealized loss (gain) reclassified into earnings, net of tax (Note 4)	2,810	(32)	2,476	(188)
Other comprehensive income (loss)	13,510	(10,205)	11,756	(13,327)
Comprehensive income	$ 20,516	$ 13,182	$ 46,541	$ 62,752