Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 11,687	$ 10,948
Other comprehensive income (loss), net of taxes:
Foreign currency translation adjustments, net of taxes	1,362	291
Unrealized gain (loss) on cash flow hedging instruments, net of taxes	1,672	(2,893)
Unrealized actuarial gain (loss) related to pension liability, net of taxes	(15)	(83)
Unrealized gain (loss) on postretirement obligation, net of taxes	(5)	(10)
Other comprehensive income (loss), net of taxes	3,014	(2,695)
Comprehensive income (loss)	$ 14,701	$ 8,253