Warrant Activity (Detail) (Warrant, USD $)	6 Months Ended
	Jun. 30, 2012
Warrant
Number of shares
Outstanding - January 1, 2012	5,452,141
Granted during the period	3,928,040
Exercised during the period
Outstanding - June 30, 2012	9,380,181
Exercisable at end of period	9,164,181
Weighted-average exercise price
Outstanding - January 1, 2012	$ 1.18
Granted during the period	$ 0.98
Exercised during the period
Outstanding - June 30, 2012	$ 1.10
Exercisable at end of period	$ 1.10