Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net loss	$ (23,360)	$ (20,145)	$ (131,891)
Other comprehensive (loss) income :
Actuarial (loss) gain on defined benefit plans	(4,529)	7,440	22,345
Reclassified net remeasurement loss	0	0	(244)
Amortization of prior service credit	(702)	(249)	(249)
Other comprehensive (loss) income	(5,231)	7,191	21,852
Comprehensive loss	$ (28,591)	$ (12,954)	$ (110,039)