Investments in Money Market Funds and Marketable Securities (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 28,169,577	$ 34,017,451
Gross Unrealized Gain	15,090	4,637
Gross Unrealized Loss	(7,637)	(9,936)
Fair Value	28,177,030	34,012,152
Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,162,239	21,792,154
Gross Unrealized Gain	10,362	4,071
Gross Unrealized Loss	(2,757)	(2,675)
Fair Value	18,169,844	21,793,550
Marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,995,361	8,165,464
Gross Unrealized Gain	3,344	435
Gross Unrealized Loss	(911)	(630)
Fair Value	8,997,794	8,165,269
Marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,166,878	13,626,690
Gross Unrealized Gain	7,018	3,636
Gross Unrealized Loss	(1,846)	(2,045)
Fair Value	9,172,050	13,628,281
Long-term marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,007,338	12,225,297
Gross Unrealized Gain	4,728	566
Gross Unrealized Loss	(4,880)	(7,261)
Fair Value	10,007,186	12,218,602
Long-term marketable securities | U.S. Government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,494,903	11,599,415
Gross Unrealized Gain	4,660	466
Gross Unrealized Loss	(269)	(7,034)
Fair Value	5,499,294	11,592,847
Long-term marketable securities | Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,512,435	625,882
Gross Unrealized Gain	68	100
Gross Unrealized Loss	(4,611)	(227)
Fair Value	$ 4,507,892	$ 625,755