Net Loss Per Share of Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2016

Net Loss Per Share Attributable to Common Stockholders

Schedule of basic and diluted net loss per share attributable to common stockholders

	Years Ended
	December 31,
	2016			2015			2014
Numerator:
Net loss attributable to common stockholders	$	(20,947	)	$	(43,230	)	$	(23,489	)
Denominator:
Weighted-average number of shares of common stock outstanding for basic and diluted net loss per share attributable to common stockholders	52,279,738			51,684,397			50,637,541
Basic and diluted net loss per share attributable to common stockholders	$	(0.40	)	$	(0.84	)	$	(0.46	)

Schedule of securities excluded from the calculation of diluted net loss per share of common stock

	Years Ended
	December 31,
	2016	2015	2014
Warrants to purchase common stock	31,130	39,824	39,824
Stock option awards	6,425,832	7,006,472	6,825,142
Restricted stock unit awards	3,750,292	2,370,803	1,161,705
Total anti-dilutive securities outstanding	10,207,254	9,417,099	8,026,671