Derivatives and Respective Fair Values Measured using Level Three Inputs (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Current	$ 1,218,000	$ 600,000
Warrant contracts issued on October 27, 2006
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Current	616,000	597,000
Warrant contracts issued on August 25, 2008
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Current	601,000	0
Warrant Series "B" contracts issued on February 18, 2011
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Current	$ 1,000	$ 3,000