Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)

v3.3.0.814
Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)
9 Months Ended
Sep. 30, 2015
USD ($)
$ / shares
shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Number of Shares, Outstanding Beginning Balance | shares 8,168,942
Number of Shares, Granted | shares 2,278,500
Number of Shares, Exercised | shares (68,759)
Number of Shares, Forfeitures | shares (91,218)
Number of Shares, Outstanding Ending Balance | shares 10,287,465
Number of Shares, Vested and expected to vest | shares 10,215,027
Number of Shares, Exercisable | shares 6,481,218
Weighted-Average Exercise Price, Outstanding at beginning of period $ 3.69
Weighted-Average Exercise Price, Granted 4.38
Weighted-Average Exercise Price, Exercised 1.98
Weighted-Average Exercise Price, Forfeitures 4.53
Weighted-Average Exercise Price, Outstanding at end of period 3.84
Weighted-Average Exercise Price, Vested and expected to vest 3.84
Weighted-Average Exercise Price, Exercisable $ 3.50
Weighted-Average Remaining Contractual Term, Outstanding 7 years 1 month 10 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest 7 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Exercisable 6 years 1 month 21 days
Aggregate Intrinsic Value, Outstanding | $ $ 8,850,855
Aggregate Intrinsic Value, Vested and expected to vest | $ 8,842,746
Aggregate Intrinsic Value, Exercisable | $ $ 8,345,365