Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 6,527	$ 12,224	$ 11,517	$ 23,341
Foreign currency translation adjustments	17,836	(17,073)	9,824	(20,452)
Net change in:
Deferred gains (losses) on cash flow hedges, net of taxes of $1,049, $(873), $1,745 and $(1,629), respectively	(2,835)	2,365	(4,704)	4,608
Unrecognized retirement obligations, net of taxes of $53, $(220), $156 and $(1,606), respectively	270	2,817	70	7,657
Other comprehensive income (loss)	15,271	(11,891)	5,190	(8,187)
Comprehensive income	$ 21,798	$ 333	$ 16,707	$ 15,154