CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 87,651	$ 80,459	$ 48,283
Other comprehensive income (loss) before reclassifications	(11,986)	28,457
Change in unrealized gain (loss) before reclassifications, net of tax
Unrealized (gain) loss reclassified into earnings, net of tax	(191)	32	11
Pension and other postretirement benefits:
Actuarial net gain (loss) incurred, net of tax (Note 4)	(1,678)	(1,481)
Amortization of gain, net of tax	(15)	131
Other comprehensive income (loss)	(13,679)	27,107	(3,804)
Comprehensive income	73,972	107,566	44,479
Foreign Currency Translation Adjustments
Other comprehensive income (loss) before reclassifications	(12,505)	28,463	(5,081)
Pension and other postretirement benefits:
Actuarial net gain (loss) incurred, net of tax (Note 4)	0	0
Amortization of gain, net of tax	0	0
Derivative Instruments Designated as Cash Flow Hedges
Other comprehensive income (loss) before reclassifications	519	(6)	0
Pension and other postretirement benefits:
Actuarial net gain (loss) incurred, net of tax (Note 4)	0	0
Amortization of gain, net of tax	(191)	32
Accumulated Other Comprehensive Income (Loss) Pension and Other Postretirement Benefits
Other comprehensive income (loss) before reclassifications	0	0
Pension and other postretirement benefits:
Actuarial net gain (loss) incurred, net of tax (Note 4)	(1,678)	(1,481)	1,106
Amortization of gain, net of tax	$ 176	$ 99	$ 160