Stockholders' Equity - Summary of Stock Option Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding at beginning of period	4,279,919
Number of Shares, Granted	177,110
Number of Shares, Exercised	(102,827)
Number of Shares, Forfeitures	(218,431)
Number of Shares, Outstanding at end of period	4,135,771
Weighted Average Exercise Price Per Share, Outstanding at beginning of period	$ 3.70
Weighted average Exercise Price Per Share, Exercised	$ 3.38
Weighted Average Exercise Price Per Share, Forfeitures	$ 2.71
Weighted Average Exercise Price Per Share, Outstanding at end of period	$ 3.79
Aggregate Intrinsic Value, Outstanding at end of period	$ 7,590,138
Officers and Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted
Weighted Average Exercise Price Per Share, Granted
Others [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted	177,110
Weighted Average Exercise Price Per Share, Granted	$ 4.38