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	$ (466,456)	$ (65,761)	$ (199,228)
Unrealized (losses) gains on marketable securities:
Holding gains (losses) arising during period, net of tax	746	(77)	(70)
Total comprehensive loss	$ (465,710)	$ (65,838)	$ (199,298)