Investments - Summary of Fair Value of Investments Measured on Recurring Basis (Detail) - USD ($)	Dec. 31, 2015	Sep. 30, 2015
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	$ 23,249,960	$ 23,921,328
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Acquisition-related contingent consideration	123,730	46,743
Total liabilities at fair value	123,730	46,743
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Corporate debt securities [Member] | Industrial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	9,688,759	9,665,243
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Corporate debt securities [Member] | Financial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	7,065,722	10,308,482
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Corporate debt securities [Member] | Utility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	602,586	1,801,803
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Commercial paper [Member] | Industrial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	698,651	1,447,655
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Commercial paper [Member] | Financial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	1,498,154	$ 698,145
Short-term [Member] | Significant Other Observable Inputs (Level 2) | Government debt securities [Member] | U.S. Treasury [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	1,551,523
Long-term [Member] | Significant Other Observable Inputs (Level 2) | Corporate debt securities [Member] | Financial [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	747,750
Long-term [Member] | Significant Other Observable Inputs (Level 2) | Government debt securities [Member] | U.S. Treasury [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of investments measured on recurring basis, total	$ 1,396,815