Derivative Financial Instruments - Reconciliation of Beginning and Ending Balances of Assets and Liabilities Measured at Fair Value Using Significant Observable Inputs (Detail) (Midcap Warrant [Member], Level 2 [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Midcap Warrant [Member] | Level 2 [Member]
Fair Value Measurement Inputs Disclosure [Line Items]
Warrant asset, Beginning balance	$ 50,300	$ 388,540
Decrease in fair value of warrants	(50,300)	(338,240)
Warrant asset, Ending balance		50,300
Warrant liability, Beginning balance	4,497,977	279,302
Decrease due to exercise of warrants	(11,266)	(1,037,237)
Expiration of warrants
Increase (Decrease) in fair value of warrants	(171,528)	5,255,912
Warrant liability, Ending balance	$ 4,315,183	$ 4,497,977
Warrant asset, Beginning balance, Number of warrants		2,000,000
Decrease in fair value of warrants, Number of warrants	(2,000,000)
Warrant asset, Ending balance, Number of warrants		2,000,000
Warrant liability, Beginning balance, Number of warrants		3,246,301
Decrease due to exercise of warrants, Number of warrants	(10,000)	(236,865)
Expiration of warrants, Number of warrants		(1,000,000)
Increase (Decrease) in fair value of warrants, Number of warrants
Warrant liability, Ending balance, Number of warrants	1,999,436	2,009,436