CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (81,394)
Other comprehensive income:
Unrealized losses on available for sale securities, net of tax of $0, $0, $0 and $0	(256)
Total comprehensive loss	$ (81,650)