Investments in Money Market Funds and Marketable Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 32,459,013	$ 34,017,451
Gross Unrealized Gain	8,889	4,637
Gross Unrealized Loss	(11,986)	(9,936)
Fair Value	32,455,916	34,012,152
Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,546,789	21,792,154
Gross Unrealized Gain	6,458	4,071
Gross Unrealized Loss	(1,849)	(2,675)
Fair Value	21,551,398	21,793,550
Marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,529,909	8,165,464
Gross Unrealized Gain	2,415	435
Gross Unrealized Loss	(120)	(630)
Fair Value	9,532,204	8,165,269
Marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,016,880	13,626,690
Gross Unrealized Gain	4,043	3,636
Gross Unrealized Loss	(1,729)	(2,045)
Fair Value	12,019,194	13,628,281
Long-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,912,224	12,225,297
Gross Unrealized Gain	2,431	566
Gross Unrealized Loss	(10,137)	(7,261)
Fair Value	10,904,518	12,218,602
Long-term marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,918,120	11,599,415
Gross Unrealized Gain	516	466
Gross Unrealized Loss	(8,279)	(7,034)
Fair Value	8,910,357	11,592,847
Long-term marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,994,104	625,882
Gross Unrealized Gain	1,915	100
Gross Unrealized Loss	(1,858)	(227)
Fair Value	$ 1,994,161	$ 625,755