Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 3,395	$ (37,424)	$ (13,538)	$ (47,511)
Other comprehensive income (loss)
Unrealized (loss) gain on available-for-sale securities, net of tax of $0	(1)	90	(64)	122
Reclassifications of gain on available-for-sale securities, included in “Other income”, net of tax of $0			3
Comprehensive income (loss)	$ 3,394	$ (37,334)	$ (13,599)	$ (47,389)