Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Product sales (including related party sales of $2,378 and $3,472 and $3,191 for the years ended December 31, 2016, 2015 and 2014)	$ 26,611	$ 25,875	$ 23,071
Licensing and royalty revenue	483	671	1,825
Total revenue	27,094	26,546	24,896
Cost of sales	12,395	12,568	11,806
Gross profit	14,699	13,978	13,090
Operating expenses:
Research and development	19,233	21,126	12,664
General and administrative	7,281	6,565	7,085
Sales and marketing	3,706	3,823	3,259
Total operating expenses	30,220	31,514	23,008
Loss from operations	(15,521)	(17,536)	(9,918)
Interest expense	(2,347)	(653)	(263)
Other income (expense), net	1,160	6	(2)
Net loss and comprehensive loss	$ (16,708)	$ (18,183)	$ (10,183)
Net loss per common share, basic and diluted	$ (3.53)	$ (7.12)	$ (4.00)
Weighted-average shares used to compute net loss per common share, basic and diluted	4,738,496	2,552,205	2,544,578