Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Level 3 Liability (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Fair Value Disclosures [Abstract]
Balance beginning of period	$ 161,494	$ 212,536
Change in fair value (included within research and development expense)	14,960	22,032
Balance end of period	$ 176,454	$ 234,568