NET LOSS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Potential Common Shares Outstanding Excluded from the Computation of Diluted Net Loss Per Share Attributable to Common Stockholders

The following table presents the potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti-dilutive (in thousands):

	Years Ended December 31,
	2017	2016	2015
Stock options to purchase common stock	8,433	8,981	8,646
Unvested restricted stock units	3,029	906	1,506
Warrants to purchase common stock	1,083	—	111
Total	12,545	9,887	10,263