Warrant Activity (Detail) (Warrant, USD $)	9 Months Ended
	Sep. 30, 2012
Warrant
Number of Shares
Number of Shares, Outstanding at beginning of period	10,430,286
Number of Shares, Granted	3,829,689
Number of Shares, Exercised
Number of Shares, Forfeited and canceled	(1,858,336)
Number of Shares, Outstanding at end of period	12,401,639
Number of Shares, Exercisable at end of period	8,571,950
Weighted average exercise price
Weighted average exercise price, Outstanding at beginning of period	$ 1.90
Weighted average exercise price, Granted	$ 1.25
Weighted average exercise price, Exercised
Weighted average exercise price, Forfeited and canceled	$ 1.53
Weighted average exercise price, Outstanding at end of period	$ 1.72
Weighted average exercise price, Exercisable at end of period	$ 1.93
Weighted average remaining contract term
Weighted average remaining contract term, Outstanding at end of period	2 years 4 months 24 days
Weighted average remaining contract term, Exercisable at end of period	1 year 3 months 18 days
Intrinsic Value
Intrinsic Value, Outstanding at end of period	$ 120,912
Intrinsic Value, Exercisable at end of the period	$ 120,912