CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (23,617)	$ 30,839	$ (266,528)	$ (43,484)
Other comprehensive loss:
Holding (losses) gains associated with marketable securities arising during period, net of tax	(167)	134	786	(253)
Total comprehensive (loss) income	$ (23,784)	$ 30,973	$ (265,742)	$ (43,737)