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)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common equivalent shares from stock warrants	2,308,808	2,318,422	491,860
Common shares from convertible redeemable preferred stock		0	22,528,878
Excluded From Earnings Per Share Calculation
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Stock options outstanding	3,233,152	4,183,000	0
Restricted stock units and restricted stock awards	310,185	45,673
Common equivalent shares from stock warrants		0	3,585,996
Common shares from convertible redeemable preferred stock		0	8,770,427
Antidilutive securities excluded from computation of earnings per share, amount, total	3,543,337	4,228,673	12,356,423