Net Income 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 (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common equivalent shares from stock warrants	0	2,308,808	2,318,422
Excluded From Earnings Per Share Calculation
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Stock options outstanding	8,796,451	3,233,152	4,183,000
Restricted stock units and restricted stock awards	1,875,325	310,185	45,673
Common equivalent shares from stock warrants	2,209,214	0	0
Shares purchased under ESPP	4,594	0	0
Antidilutive securities excluded from computation of earnings per share, amount, total	12,885,584	3,543,337	4,228,673