Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 5,831	$ (7,399)	$ 11,117	$ (1,683)
Foreign currency translation adjustments	1,426	(33,223)	(3,379)	(20,476)
Net change in:
Deferred gains on cash flow hedges, net of taxes of $78, $(1,719), $(757) and $(1,719), respectively	21	4,549	2,243	2,747
Unrecognized retirement obligations, net of taxes of $358, $(965), $213 and $(1,942), respectively	4,352	3,021	4,840	6,096
Other comprehensive income (loss)	5,799	(25,653)	3,704	(11,633)
Comprehensive income (loss)	$ 11,630	$ (33,052)	$ 14,821	$ (13,316)