Investments in Money Market Funds and Marketable Securities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 28,162,159	$ 34,017,451
Gross Unrealized Gain	9,264	4,637
Gross Unrealized Loss	(3,957)	(9,936)
Fair Value	28,167,466	34,012,152
Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,267,093	21,792,154
Gross Unrealized Gain	4,273	4,071
Gross Unrealized Loss	(849)	(2,675)
Fair Value	16,270,517	21,793,550
Marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,286,273	8,165,464
Gross Unrealized Gain	2,220	435
Gross Unrealized Loss	(119)	(630)
Fair Value	7,288,374	8,165,269
Marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,980,820	13,626,690
Gross Unrealized Gain	2,053	3,636
Gross Unrealized Loss	(730)	(2,045)
Fair Value	8,982,143	13,628,281
Long-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,895,066	12,225,297
Gross Unrealized Gain	4,991	566
Gross Unrealized Loss	(3,108)	(7,261)
Fair Value	11,896,949	12,218,602
Long-term marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,365,077	11,599,415
Gross Unrealized Gain	3,144	466
Gross Unrealized Loss	(888)	(7,034)
Fair Value	7,367,333	11,592,847
Long-term marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,529,989	625,882
Gross Unrealized Gain	1,847	100
Gross Unrealized Loss	(2,220)	(227)
Fair Value	$ 4,529,616	$ 625,755