Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net loss	$ (26,407)	$ (38,081)	$ (91,581)	$ (167,269)
Other comprehensive income (loss):
Change in pension plan and supplemental pension plan liability, net of tax of $0, $0.2 million, $0 and $0.4 million, respectively	(207)	525	(485)	1,342
Total comprehensive loss	$ (26,614)	$ (37,556)	$ (92,066)	$ (165,927)