Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net loss before income taxes:
United States	$ (153,620)	$ (203,230)	$ (133,113)
Non-U.S.	(46,051)	(29,336)	(13,750)
Loss before income taxes	(199,671)	(232,566)	(146,863)
Current:
United States	(90)	3	(24)
Non-U.S.	0	0	0
Total	(90)	3	(24)
Deferred:
United States	0	0	(1,734)
Non-U.S.	0	0	0
Total	0	0	(1,734)
Provision for income taxes	$ (90)	$ 3	$ (1,758)
Effective tax rate (in percentage)	0.05%	0.00%	1.20%