Consolidated Statements of Preferred Stock and Stockholders' Deficit (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	IPO [Member] USD ($)	Follow-on public stock offering [Member] USD ($)	Common stock USD ($)	Common stock IPO [Member] USD ($)	Common stock Follow-on public stock offering [Member] USD ($)	Additional paid-in capital USD ($)	Additional paid-in capital IPO [Member] USD ($)	Additional paid-in capital Follow-on public stock offering [Member] USD ($)	Accumulated other comprehensive gain USD ($)	Accumulated deficit USD ($)	Restricted stock units USD ($)	Restricted stock units Common stock	Restricted stock units Additional paid-in capital USD ($)	Cashless Exercise [Member] Common stock	Cash Exercise [Member] USD ($)	Cash Exercise [Member] Common stock	Cash Exercise [Member] Additional paid-in capital USD ($)
Balance at Dec. 31, 2010	$ (50,364)			$ 1			$ 4,017			$ 0	$ (54,382)
Balance (shares) at Dec. 31, 2010				2,777,094
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)				1,005,366
Exercise of stock options	1,224			0			1,224
Vesting of early exercised stock options	217						217
Proceeds from Warrant Exercises	0
Non-employee stock-based compensation expense	457						457
Employee stock-based compensation expense	1,001						1,001
ExperiaHealth performance awards	549						549
Repurchase of early exercised options (shares)				(1,970)
Repurchase of early exercised options	(4)						(4)
Net loss	(2,479)										(2,479)
Change in unrealized gain on available-for-sale securities	0
Balance at Dec. 31, 2011	(49,399)			1			7,461			0	(56,861)
Balance (shares) at Dec. 31, 2011				3,780,490
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of preferred stock into common stock (shares)				12,937,750
Conversion of preferred stock to common stock	53,356			4			53,352
Shares sold at public offering					5,000,000	1,337,500
Issuance of common stock in a public offering		70,535	35,975		2	0		70,533	35,975
Reclassification of preferred stock warrant liability into additional paid-in capital upon initial public offering	3,141						3,141
Exercise of stock options (shares)				1,073,732
Exercise of stock options	1,684						1,684
ESPP, Shares Purchased for Award	0
Vesting of early exercised stock options	307						307
Exercise of common stock warrants															78,487
Proceeds from Warrant Exercises	0
Issuance of restricted stock awards				24,152
Non-employee stock-based compensation expense	29						29
Employee stock-based compensation expense	4,203						4,203
Income tax benefits from employee stock plans	406						406
Repurchase of early exercised options (shares)				(2,755)
Repurchase of early exercised options	(10)						(10)
Net loss	2,893										2,893
Change in unrealized gain on available-for-sale securities	5									5
Balance at Dec. 31, 2012	123,125			7			177,081			5	(53,968)
Balance (shares) at Dec. 31, 2012				24,229,356
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	420,492			420,492
Exercise of stock options	1,657						1,657
Vested, Number of Shares												117,245	71,824
RSUs released and tax settlement												(703)		(703)
ESPP, Shares Purchased for Award	215,039			215,039
Stock Issued During Period, Value, Employee Stock Purchase Plan	2,993						2,993
Vesting of early exercised stock options	123						123
Exercise of common stock warrants																	34,142
Proceeds from Warrant Exercises	226															226		226
Employee stock-based compensation expense	8,667						8,667
Income tax benefits from employee stock plans	(64)						(64)
Repurchase of early exercised options (shares)				(3,713)
Repurchase of early exercised options	(14)						(14)
Net loss	(10,465)										(10,465)
Change in unrealized gain on available-for-sale securities	18									18
Balance at Dec. 31, 2013	$ 125,563			$ 7			$ 189,966			$ 23	$ (64,433)
Balance (shares) at Dec. 31, 2013				24,967,140