Fair Value of Financial Instruments - Summary of Company's Financial Assets Carried at Fair Value (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Jan. 06, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	$ 176,454	$ 161,494	$ 234,568	$ 212,536
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	176,454	161,494
Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	48,995,405	49,209,098
Recurring [Member] | Bank Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,038,325	5,037,169
Recurring [Member] | U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities - U.S. government agency securities	100,357,728	100,160,889
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	48,995,405	49,209,098
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Recurring [Member] | U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities - U.S. government agency securities	95,358,878	90,138,019
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member] | Bank Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,038,325	5,037,169
Significant Other Observable Inputs (Level 2) [Member] | Recurring [Member] | U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term marketable securities - U.S. government agency securities	4,998,850	10,022,870
Significant Unobservable Inputs (Level 3) [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	$ 176,454	$ 161,494