Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Observable Inputs (Level 2) (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value included in earnings	$ (44,000)	$ 1,179,151	$ (474,000)	$ 2,554,252
Fair Value, Measurements, Recurring | Warrants | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance at January 1, 2012			615,000
Change in fair value included in earnings			474,000
Exercise of warrants			(385,000)
Balance at June 30, 2012	$ 704,000		$ 704,000