Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Total revenues	$ 14,967	$ 12,319	$ 29,637	$ 27,901
Costs and operating expenses:
Cost of product revenue	1,699	2,772	4,240	7,163
Research and development	10,853	8,274	21,820	16,290
Selling, general and administrative	8,522	7,896	17,512	16,311
Total costs and operating expenses	21,074	18,942	43,572	39,764
Loss from operations	(6,107)	(6,623)	(13,935)	(11,863)
Interest income	57	220	323	450
Other income (expenses), net	13	(88)	(72)	(211)
Loss before income taxes	(6,037)	(6,491)	(13,684)	(11,624)
Provision for income taxes	307	16	312	19
Net loss	$ (6,344)	$ (6,507)	$ (13,996)	$ (11,643)
Net loss per share, basic and diluted (usd per share)	$ (0.11)	$ (0.12)	$ (0.24)	$ (0.21)
Weighted average common stock shares used in computing net loss per share, basic and diluted (shares)	59,000	54,954	58,944	54,564
Product Sales [Member]
Revenues:
Total revenues	$ 4,504	$ 6,249	$ 9,604	$ 14,236
Research and Development Revenue [Member]
Revenues:
Total revenues	$ 10,463	$ 6,070	$ 20,033	$ 13,665