Major Category of Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring	Jun. 30, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	$ 28,991,544
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	4,613,256
U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	13,319,827
Corporate and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	11,058,461
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	13,081,488
Quoted prices in active markets for identical assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	4,613,256
Quoted prices in active markets for identical assets (Level 1) | U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	8,468,232
Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	15,910,056
Significant other observable inputs (Level 2) | U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	4,851,595
Significant other observable inputs (Level 2) | Corporate and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	$ 11,058,461