Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Income (Loss)
Net income (loss)	$ (8,391)	$ (78,733)	$ (407,088)
Available-for-sale securities:
Change in net unrealized gains or losses	(53)	49	11
Unrealized gain (loss) on available-for-sale securities	(53)	49	11
Currency translation adjustments:
Change in currency translation adjustments	5	(19)	5
Reclassification adjustments for net (gains) losses included in net income		44	(8)
Net changes related to currency translation adjustments	5	25	(3)
Total other comprehensive income (loss), net of tax	(48)	74	8
Total comprehensive income (loss)	$ (8,439)	$ (78,659)	$ (407,080)