Assumptions Used In Binomial and Monte Carlo Valuation Model (Detail)	Dec. 31, 2009 Y	Mar. 31, 2013 Binomial/Monte Carlo Option Pricing Model Y	Mar. 31, 2012 Binomial/Monte Carlo Option Pricing Model Y	Mar. 31, 2013 Binomial/Monte Carlo Option Pricing Model Minimum Y	Mar. 31, 2012 Binomial/Monte Carlo Option Pricing Model Minimum Y	Mar. 31, 2012 Binomial/Monte Carlo Option Pricing Model Maximum Y
Class of Warrant or Right [Line Items]
Risk-free interest rate	2.14%			0.25%	0.07%	0.42%
Expected volatility	105.00%			70.00%	60.00%	80.00%
Expected dividend yield	0.00%	0.00%	0.00%
Expected life in years	5	12	12	1.69	0.17	2.69