CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
BALANCE at Dec. 31, 2016	$ 9	$ 383,193	$ (342,385)	$ 40,817
BALANCE, Shares at Dec. 31, 2016	89,066,031
Issuance of common stock for stock option exercises		1,012		$ 1,012
Issuance of common stock for stock option exercise, Shares	392,606			392,606
Vesting of early exercised stock options, Shares	937
Issuance of common stock pursuant to the Employee Stock Purchase Plan		2,110		$ 2,110
Issuance of common stock pursuant to the Employee Stock Purchase Plan, Shares	793,210
Issuance of common shares pursuant to the Employee Stock-Settled Bonus Plan		8,272		8,272
Issuance of common stock shares pursuant to the Employee Stock-Settled Bonus Plan, shares	1,688,097
Shares withheld for net settlement of Employee Stock-Settled Bonus Plans		(3,149)		(3,149)
Shares withheld for net settlement of Employee Stock-Settled Bonus Plans, Shares	(677,547)
Vesting of restricted stock units, Shares	917,106
Stock-based compensation		4,882		4,882
Net loss			(12,833)	(12,833)
BALANCE at Mar. 31, 2017	$ 9	$ 396,320	$ (355,218)	$ 41,111
BALANCE, Shares at Mar. 31, 2017	92,180,440