Investments - Summary of Amortized Cost, Unrealized Gains and Fair Value of Short-term Investments (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 64,761,846	$ 42,802,547
Unrealized Gain	50,805	4,883
Unrealized Loss	(1,174)	(15,880)
Fair Value	64,811,477	42,791,550
Corporate Bonds and Notes [Member] | Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	64,761,846	42,011,286
Unrealized Gain	50,805	4,883
Unrealized Loss	(1,174)	(13,387)
Fair Value	$ 64,811,477	42,002,782
Corporate Bonds and Notes [Member] | Long-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		791,261
Unrealized Loss		(2,493)
Fair Value		$ 788,768