Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 16,946	$ 9,984	$ 44,526	$ 28,301
Costs and operating expenses:
Cost of product revenue	3,791	3,976	10,228	10,768
Research and development	7,917	8,055	22,464	20,242
Selling, general and administrative	7,344	7,989	22,485	21,141
Total costs and operating expenses	19,052	20,020	55,177	52,151
Loss from operations	(2,106)	(10,036)	(10,651)	(23,850)
Interest income	199	28	444	96
Other expenses, net	(80)	(68)	(221)	(80)
Loss before income taxes	(1,987)	(10,076)	(10,428)	(23,834)
Provision for (benefit from) income taxes	1	150	(11)	132
Net loss	$ (1,988)	$ (10,226)	$ (10,417)	$ (23,966)
Net loss per share, basic and diluted (usd per share)	$ (0.04)	$ (0.21)	$ (0.20)	$ (0.53)
Weighted average common stock shares used in computing net loss per share, basic and diluted (shares)	53,597	48,147	51,609	45,568
Product Sales [Member]
Revenues:
Total revenues	$ 8,405	$ 6,948	$ 18,291	$ 19,134
Research and Development Revenue [Member]
Revenues:
Total revenues	$ 8,541	$ 3,036	$ 26,235	$ 9,167