Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 60,230	$ 75,354
Accounts receivable	1,578	1,970
Inventory	27	25
Prepaid expenses	781	633
Total current assets	62,616	77,982
Property and equipment, net	481	401
Deferred offering costs	200	0
Total assets	63,297	78,383
Current liabilities:
Accounts payable	2,423	6,903
Accrued liabilities	2,506	5,001
Deferred rent, current	47	43
Total current liabilities	4,976	11,947
Other noncurrent liabilities	73	90
Commitments and contingencies:
Convertible preferred stock, $0.001 par value per share; 10,000,000 shares authorized at March 31, 2015 (unaudited) and December 31, 2014; zero shares issued and outstanding at March 31, 2015 (unaudited) and December 31, 2014; liquidation preference of zero at March 31, 2015 (unaudited) and December 31, 2014	0	0
Stockholders’ equity:
Common stock, $0.001 par value per share; 100,000,000 shares authorized at March 31, 2015(unaudited) and December 31, 2014; 16,979,688 and 16,878,817 shares issued and outstanding at March 31, 2015 (unaudited) and December 31, 2014, respectively	17	17
Additional paid-in capital	158,400	157,092
Accumulated deficit	(100,169)	(90,763)
Total stockholders’ equity	58,248	66,346
Total liabilities, convertible preferred stock and stockholders’ equity	$ 63,297	$ 78,383