CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 24,293	$ 17,329	$ 52,692	$ 43,465
Foreign currency translation adjustment	2,182	(15,294)	(2,075)	(8,293)
Derivative instrument designated as cash flow hedge:
Change in unrealized gain (loss) before reclassifications, net of tax (Note 4)	(810)	349	(1,204)	1,153
Unrealized (gain) loss reclassified into earnings, net of tax (Note 4)	(62)	(29)	(156)	(56)
Pension and other postretirement benefits:
Amortization of loss, net of tax (Note 4)	157	44	313	87
Other comprehensive income (loss)	1,467	(14,930)	(3,122)	(7,109)
Comprehensive income	$ 25,760	$ 2,399	$ 49,570	$ 36,356