Net Income (Loss) Per Share - Number of Outstanding Stock Options, Warrants to Purchase Common Preferred Stock and Convertible Redeemable Preferred Stock Excluded from Computation of Diluted Net Income (Loss) Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common equivalent shares from stock warrants (in shares)	0	2,228,386	0	0
Excluded from earnings per share calculation
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options outstanding (in shares)	9,648,039	4,651,910	9,379,323	7,436,319
Restricted stock units and restricted stock awards (in shares)	2,546,119	327,405	2,656,439	718,507
Common equivalent shares from stock warrants (in shares)	0	0	462,480	2,224,271
Shares purchased under ESPP (in shares)	0	0	5,806	9,443
Antidilutive securities excluded from computation of earnings per share, amount, total (in shares)	12,194,158	4,979,315	12,504,048	10,388,540