Fair Value Measurements - Fair Value Hierarchy for Financial Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Liabilities:
Accrued warrant liability	$ 1,241,311	$ 4,105,659
Compensatory stock options not yet issued	309,450
Total liabilities	1,550,761	4,105,659
Level 1 [Member]
Liabilities:
Accrued warrant liability
Compensatory stock options not yet issued
Total liabilities
Level 2 [Member]
Liabilities:
Accrued warrant liability
Compensatory stock options not yet issued
Total liabilities
Level 3 [Member]
Liabilities:
Accrued warrant liability	1,241,311	4,105,659
Compensatory stock options not yet issued	309,450
Total liabilities	$ 1,550,761	$ 4,105,659