Condensed Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Collaborative research and development and other revenue	$ 434	$ 419
Product revenue, net	4,133	3,189
Total revenues	4,567	3,608
Operating expenses:
Cost of product revenues	1,543	1,242
Research and development	7,548	6,625
Selling, general and administrative	3,043	3,062
Total operating expenses	12,134	10,929
Loss from operations	(7,567)	(7,321)
Other income (expense):
Interest and other income	36	27
Interest expense	(583)	(558)
Net other income (expense)	(547)	(531)
Net loss	(8,114)	(7,852)
Net change in unrealized gain (loss) on available-for-sale securities, net of reclassification adjustments and taxes	(2)	17
Total comprehensive loss	$ (8,116)	$ (7,835)
Net loss per share
Basic	$ (0.06)	$ (0.06)
Diluted	$ (0.06)	$ (0.06)
Weighted-average shares used in computing net loss per share
Basic	141,815	122,149
Diluted	141,815	122,149