CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 23,387	$ 19,734	$ 76,079	$ 63,199
Foreign currency translation adjustment	(10,187)	(1,608)	(12,262)	(9,901)
Derivative instrument designated as cash flow hedge:
Change in unrealized gain (loss) before reclassifications, net of tax (Note 4)	(158)	263	(1,362)	1,416
Unrealized (gain) reclassified into earnings, net of tax (Note 4)	(32)	(52)	(188)	(108)
Pension and other postretirement benefits:
Amortization of loss, net of tax (Note 4)	172	44	485	131
Other comprehensive income (loss)	(10,205)	(1,353)	(13,327)	(8,462)
Comprehensive income	$ 13,182	$ 18,381	$ 62,752	$ 54,737