Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

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

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders during the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share data):

	Year Ended December 31,
	2016			2015			2014
Net loss	$	(41,708	)	$	(64,911	)	$	(48,429	)
Weighted-average common shares outstanding	84,483			81,914			70,837
Net loss per share — basic and diluted	$	(0.49	)	$	(0.79	)	$	(0.68	)

Schedule of anti-dilutive shares excluded from the calculation of diluted net loss per share attributable to common stockholders

The following table presents the number of anti-dilutive shares excluded from the calculation of diluted net loss per share attributable to common stockholders at December 31, 2016, 2015 and 2014 (in thousands):

	December 31,
	2016	2015	2014
Options to purchase common stock	24,542	24,278	25,590
Common stock warrants	1,459	1,631	3,926
Unvested restricted stock awards	4,339	3,747	828
Total shares excluded from net loss per share attributable to common stockholders	30,340	29,656	30,344