Summary of Stock Option Activity (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Number of shares
Outstanding, December 31, 2011	1,870,846
Granted (Unaudited)	423,500
Exercised (Unaudited)
Forfeited (Unaudited)	(702,186)
Outstanding, June 30, 2012 (Unaudited)	1,592,160	1,870,846
Exercisable, June 30, 2012 (Unaudited)	911,184
Weighted Average Exercise Price
Outstanding, December 31, 2011	$ 3.67
Granted (Unaudited)	$ 1.82
Exercised (Unaudited)
Forfeited (Unaudited)	$ 4.37
Outstanding, June 30, 2012 (Unaudited)	$ 2.87	$ 3.67
Exercisable, June 30, 2012 (Unaudited)	$ 3.63
Remaining Contractual Life (years)
Outstanding, December 31, 2011	7 years 10 months 10 days	7 years 4 months 24 days
Granted, June 30, 2012 (Unaudited)	9 years 8 months 5 days
Outstanding, June 30, 2012 (Unaudited)	7 years 10 months 10 days	7 years 4 months 24 days
Exercisable, June 30, 2012 (Unaudited)	6 years 9 months
Aggregate Intrinsic Value
Outstanding, December 31, 2011	$ 66,976
Outstanding, June 30, 2012 (Unaudited)		66,976
Exercisable, June 30, 2012 (Unaudited)