Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (237,203)	$ (32,417)	$ (63,146)
Other comprehensive income (loss) before tax:
Foreign currency translation adjustment	3,697	3,865	(9,241)
Foreign currency hedge	(1,198)	282	658
Defined benefit pension plans
Net actuarial gain (loss) arising during period	0	(421)	109
Settlement cost during period	0	226	0
Prior service cost arising during period	0	0	(669)
Amortization of prior service cost	0	33	0
Amortization of net actuarial (gain) loss	0	0	(78)
Other comprehensive income (loss)	2,499	3,985	(9,221)
Tax (provision) benefit attributable to other comprehensive income (loss)	13	217	(3,045)
Other comprehensive income (loss), net of tax	2,512	4,202	(12,266)
Total comprehensive loss	$ (234,691)	$ (28,215)	$ (75,412)