Quarterly report pursuant to Section 13 or 15(d)

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

v3.4.0.3
Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)
3 Months Ended
Mar. 31, 2016
$ / shares
shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Number of Shares, Outstanding Beginning Balance 9,032,136
Number of Shares, Granted 2,735,000
Number of Shares, Exercised 0
Number of Shares, Forfeitures (206,043)
Number of Shares, Outstanding Ending Balance 11,561,093
Number of Shares, Vested and expected to vest 11,434,385
Number of Shares, Exercisable 7,085,144
Weighted-Average Exercise Price, Outstanding at beginning of period | $ / shares $ 3.77
Weighted-Average Exercise Price, Granted | $ / shares 0.54
Weighted-Average Exercise Price, Forfeitures | $ / shares 3.78
Weighted-Average Exercise Price, Outstanding at end of period | $ / shares 3.01
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares 3.03
Weighted-Average Exercise Price, Exercisable | $ / shares $ 3.65
Weighted-Average Remaining Contractual Term, Outstanding 6 years 6 months 11 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest 6 years 6 months
Weighted-Average Remaining Contractual Term, Exercisable 4 years 8 months 27 days