CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ 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]
Product revenue, net	$ 96,131	$ 86,327	$ 267,156	$ 268,139
Operating expenses:
Cost of sales	1,275	1,216	3,927	4,328
Research and development	28,091	33,869	85,345	86,489
Selling, general and administrative	30,533	26,523	90,071	79,630
Total operating expenses	59,899	61,608	179,343	170,447
Income from operations	36,232	24,719	87,813	97,692
Interest and other income	72	622	457	3,103
Income before income taxes	36,304	25,341	88,270	100,795
Income tax expense	(5,833)	(3,716)	(7,811)	(20,778)
Net income	30,471	21,625	80,459	80,017
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale investments, net of tax effect of $8, $109, $85 and $(81), respectively	(23)	(347)	(265)	259
Foreign currency translation gain (loss), net of tax	(77)	84	(35)	57
Total comprehensive income	$ 30,371	$ 21,362	$ 80,159	$ 80,333
Basic net income per share (in dollars per share)	$ 0.26	$ 0.19	$ 0.69	$ 0.70
Diluted net income per share (in dollars per share)	$ 0.24	$ 0.17	$ 0.63	$ 0.65
Weighted-average shares outstanding used in computing net income per share
Basic (in shares)	115,791	115,734	116,297	115,107
Diluted (in shares)	125,136	124,464	127,173	123,337