Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (1,390)	$ (2,257)	$ 5,997	$ (26,065)
Available-for-sale investments
Net change in unrealized gain (loss) on available-for-sale investments	0	(2)	0	(2)
Reclassification adjustment for losses on investments recognized during the period	0	0	0	63
Net change in unrealized gain (loss) on available-for-sale investments	0	(2)	0	61
Other comprehensive gain (loss), net of tax	0	(2)	0	61
Comprehensive income (loss)	$ (1,390)	$ (2,259)	$ 5,997	$ (26,004)