CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 28,399	$ 26,136
Foreign currency translation adjustment	(4,257)	7,000
Derivative instrument designated as cash flow hedge:
Change in unrealized gain (loss) before reclassifications, net of tax (Note 4)	(394)	805
Unrealized (gain) loss reclassified into earnings, net of tax (Note 4)	(94)	(27)
Pension and other postretirement benefits:
Amortization of loss, net of tax (Note 4)	156	43
Other comprehensive income (loss)	(4,589)	7,821
Comprehensive income	$ 23,810	$ 33,957

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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