Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (51,983)	$ (345,973)
Other comprehensive income (loss), net of taxes:
Foreign currency translation adjustments, net of tax	(335)	(113)
Net change in pension and benefit plan liabilities, net of tax	6,925
Net change in unrealized loss on derivative financial instruments, net of tax		(331)
Other comprehensive income (loss), net of taxes	6,590	(444)
Comprehensive loss	$ (45,393)	$ (346,417)