Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 21,298	$ (21,541)	$ (177,604)
Foreign currency translation adjustments	33,821	(6,724)	(27,783)
Net change in:
Deferred gains (losses) on cash flow hedges, net of taxes of $2,507, $(737), and $(2,353), respectively	(6,812)	2,117	6,291
Unrecognized retirement obligations, net of taxes of $158, $(22,927), and $(13,898), respectively	(7,766)	64,151	47,025
Other comprehensive income	19,243	59,544	25,533
Comprehensive income (loss)	$ 40,541	$ 38,003	$ (152,071)