Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net loss before income taxes:
United States	$ (143,349)	$ (153,620)	$ (203,230)
Non-U.S.	(34,507)	(46,051)	(29,336)
Loss before income taxes	(177,856)	(199,671)	(232,566)
Current:
United States	(33)	(90)	3
Non-U.S.	5,278	0	0
Total	5,245	(90)	3
Deferred:
United States	0	0	0
Non-U.S.	0	0	0
Total	0	0	0
Provision for income taxes	$ 5,245	$ (90)	$ 3
Effective tax rate (in percentage)	(2.95%)	0.05%	0.00%