Fair Value Measurements - Financial Assets or Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value Measurements Recurring [Member] - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 72,135,362	$ 80,516,167
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	8,812,483	13,567,573
Corporate commercial paper, bonds and notes	4,501,918	9,999,090
Municipal bonds	390,000	7,849,657
Quoted Prices in Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	21,327,011	18,212,490
Quoted Prices in Active Markets (Level 1) [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	8,812,483	13,567,573
Corporate commercial paper, bonds and notes	2,752,215	2,000,920
Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	50,808,351	62,303,677
Other Observable Inputs (Level 2) [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes	1,749,703	7,998,170
Municipal bonds	390,000	7,849,657
Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes	58,430,961	49,099,847
Short-term Investments [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes	9,762,313	2,643,997
Short-term Investments [Member] | Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes	$ 48,668,648	$ 46,455,850