Investments in Money Market Funds and Marketable Securities (Detail) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 24,376,423	$ 26,643,408
Gross Unrealized Gain	5,672	6,403
Gross Unrealized Loss	(3,807)	(9,392)
Fair Value	24,378,288	26,640,419
Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,153,147	23,089,499
Gross Unrealized Gain	5,400	6,403
Gross Unrealized Loss	(3,727)	(5,693)
Fair Value	23,154,820	23,090,209
Marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,092,702	12,716,167
Gross Unrealized Gain	4,006	2,174
Gross Unrealized Loss	(349)	(2,072)
Fair Value	12,092,359	12,716,269
Marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,060,445	10,373,332
Gross Unrealized Gain	1,394	4,229
Gross Unrealized Loss	(3,378)	(3,621)
Fair Value	11,058,461	10,373,940
Long-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,223,276	3,553,909
Gross Unrealized Gain	272
Gross Unrealized Loss	(80)	(3,699)
Fair Value	1,223,468	3,550,210
Long-term marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,223,276	1,227,843
Gross Unrealized Gain	272
Gross Unrealized Loss	(80)	(207)
Fair Value	$ 1,223,468	1,227,636
Long-term marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,326,066
Gross Unrealized Loss		(3,492)
Fair Value		$ 2,322,574