CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 14,520	$ 24,293	$ 27,779	$ 52,692
Foreign currency translation adjustment	5,629	2,182	(1,265)	(2,075)
Pension and other postretirement benefits:
Pension settlement benefits, net of tax (Note 4)	(48)	0	(48)	0
Actuarial net gain incurred, net of tax (Note 4)	626	0	626	0
Amortization of loss, net of tax (Note 4)	67	157	133	313
Derivative instrument designated as cash flow hedge:
Change in unrealized gain (loss) before reclassifications, net of tax (Note 4)	383	(810)	(866)	(1,204)
Unrealized gain reclassified into earnings, net of tax (Note 4)	(267)	(62)	(334)	(156)
Other comprehensive income (loss)	6,390	1,467	(1,754)	(3,122)
Comprehensive income	$ 20,910	$ 25,760	$ 26,025	$ 49,570