Summary of Options Outstanding and Exercisable (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share Based Compensation Plans [Line Items]
Options Outstanding, Number Outstanding | shares	5,751,778
Options Outstanding, Weighted Average Remaining Remaining Contractual Life (Years)	5 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 1.05
Options Exercisable, Number Exercisable | shares	5,078,611
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 1.00
Exercise Price 0.00-1.00 [Member]
Share Based Compensation Plans [Line Items]
Options Outstanding, Number Outstanding | shares	2,617,778
Options Outstanding, Weighted Average Remaining Remaining Contractual Life (Years)	6 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 0.50
Options Exercisable, Number Exercisable | shares	2,451,111
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 0.50
Exercise Price 1.01-2.00 [Member]
Share Based Compensation Plans [Line Items]
Options Outstanding, Number Outstanding | shares	2,899,000
Options Outstanding, Weighted Average Remaining Remaining Contractual Life (Years)	3 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 1.42
Options Exercisable, Number Exercisable | shares	2,550,000
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 1.41
Exercise Price 2.01-3.00 [Member]
Share Based Compensation Plans [Line Items]
Options Outstanding, Number Outstanding | shares	210,000
Options Outstanding, Weighted Average Remaining Remaining Contractual Life (Years)	8 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 2.43
Options Exercisable, Number Exercisable | shares	52,500
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 2.43
Exercise Price 3.01-4.30 [Member]
Share Based Compensation Plans [Line Items]
Options Outstanding, Number Outstanding | shares	25,000
Options Outstanding, Weighted Average Remaining Remaining Contractual Life (Years)	8 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 4.30
Options Exercisable, Number Exercisable | shares	25,000
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 4.30