Condensed Consolidated Statements of Comprehensive Income ( Loss) - 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)	$ 20,267	$ (15,150)	$ (1,420)	$ (27,099)
Unrealized gain on available-for-sale securities	271	357	170	551
Comprehensive income (loss)	$ 20,538	$ (14,793)	$ (1,250)	$ (26,548)