CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 5,947	$ 100,423	$ 15,147	$ 111,337
Other comprehensive income (loss):
Net foreign currency translation gain (loss)	32	(19)	29	(17)
Change in net unrealized gain (loss) on marketable securities	(323)	(89)	130	294
Tax benefit (provision) on other comprehensive income (loss)	74	(67)	(29)	(67)
Other comprehensive income (loss), net of tax	(217)	(175)	130	210
Comprehensive income	$ 5,730	$ 100,248	$ 15,277	$ 111,547