Summary of Significant Accounting Policies - Financial Assets or Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value Measurements Recurring [Member] - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 80,516,167	$ 48,301,444
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	13,567,573	4,419,894
Corporate commercial paper, bonds and notes	9,999,090
Municipal bonds	7,849,657	1,090,000
Short-and Long-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes		42,791,550
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	18,212,490	44,511,694
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	13,567,573	4,419,894
Corporate commercial paper, bonds and notes	2,000,920
Quoted Prices in Active Markets (Level 1) [Member] | Short-and Long-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes		40,091,800
Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	62,303,677	3,789,750
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	7,998,170
Municipal bonds	7,849,657	1,090,000
Other Observable Inputs (Level 2) [Member] | Short-and Long-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes		$ 2,699,750
Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate commercial paper, bonds and notes	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	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	$ 46,455,850