Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (2,416)	$ 5,831	$ 4,990	$ 11,117
Foreign currency translation adjustments	5,891	1,426	(8,012)	(3,379)
Net change in:
Deferred gains (losses) on cash flow hedges, net of taxes of $295, $78, $696 and $(756), respectively	(552)	21	(1,869)	2,243
Unrecognized retirement obligations, net of taxes of $52, $(1,241), $103 and $(1,386), respectively	(99)	4,352	(200)	4,840
Other comprehensive income (loss)	5,240	5,799	(10,081)	3,704
Comprehensive income (loss)	$ 2,824	$ 11,630	$ (5,091)	$ 14,821