Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)
6 Months Ended
Jun. 30, 2016
USD ($)
$ / shares
shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Number of Shares, Outstanding Beginning Balance 9,032,136
Number of Shares, Granted 2,945,000
Number of Shares, Exercised 0
Number of Shares, Forfeitures (341,939)
Number of Shares, Outstanding Ending Balance 11,635,197
Number of Shares, Vested and expected to vest 11,527,107
Number of Shares, Exercisable 7,444,072
Weighted-Average Exercise Price, Outstanding at beginning of period | $ / shares $ 3.77
Weighted-Average Exercise Price, Granted | $ / shares 0.53
Weighted-Average Exercise Price, Forfeitures | $ / shares 3.07
Weighted-Average Exercise Price, Outstanding at end of period | $ / shares 2.97
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares 2.99
Weighted-Average Exercise Price, Exercisable | $ / shares $ 3.61
Weighted-Average Remaining Contractual Term, Outstanding 6 years 3 months 26 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest 6 years 3 months 15 days
Weighted-Average Remaining Contractual Term, Exercisable 4 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding | $ $ 300,142
Aggregate Intrinsic Value, Vested and expected to vest | $ 292,477
Aggregate Intrinsic Value, Exercisable | $ $ 16,920