Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (307,063)	$ (121,949)	$ (63,708)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net of tax	3,804	258	(598)
Foreign currency translation	0	(1,001)	2,623
Total other comprehensive income (loss), net of tax	3,804	(743)	2,025
Comprehensive loss attributable to common stockholders	$ (303,259)	$ (122,692)	$ (61,683)