CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (65,761)	$ (199,228)	$ (2,483)
Unrealized (losses) gains on marketable securities:
Holding (losses) gains arising during period, net of tax	(77)	(70)	261
Reclassification adjustment for gains (losses) included in net (loss) income, net of tax	0	0	106
Net unrealized (losses) gains on securities	(77)	(70)	367
Total comprehensive loss	$ (65,838)	$ (199,298)	$ (2,116)