Warrants (Detail) - Assumptions used in determining fair value of liability-classified warrants (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Weighted average grant date fair value (in Dollars per share)	$ 2.91	$ 5.85
Black-Scholes [Member] | Warrant [Member]
Expected volatility	91.60%
Risk-free interest rate	0.90%
Dividend yield
Expected life in years	6 years
Weighted average grant date fair value (in Dollars per share)	$ 1.57
Warrant [Member]
Expected volatility	71.30%	58.80%
Risk-free interest rate	0.30%	0.70%