CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Product revenue, net	$ 93,247	$ 64,829
Operating expenses:
Cost of sales	1,878	1,240
Research and development	26,123	20,244
Selling, general and administrative	27,535	24,389
Total operating expenses	55,536	45,873
Income from operations	37,711	18,956
Interest and other income	1,471	1,097
Income before income taxes	39,182	20,053
Income tax expense	(9,117)	(1,779)
Net income	30,065	18,274
Other comprehensive income (loss):
Net unrealized gain on available-for-sale investments, net of tax impact of $(20) and $(52), respectively	61	164
Foreign currency translation loss, net of tax	(12)	0
Total comprehensive income	$ 30,114	$ 18,438
Basic net income per share (in dollars per share)	$ 0.26	$ 0.16
Diluted net income per share (in dollars per share)	$ 0.25	$ 0.15
Weighted-average shares outstanding used in computing net income per share
Basic (in shares)	114,575	114,844
Diluted (in shares)	122,226	123,895