Comprehensive Loss - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Income Loss [Abstract]
Comprehensive loss	$ (7,404,427)	$ (5,356,878)	$ (21,337,798)	$ (16,594,090)