Fair Value Measurements - Fair Value Measurements for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities	$ 4,173,943	$ 4,096,363
Contingent consideration	3,970,931	1,595,273	173,621
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	132,510,610	19,114,444
Derivative liabilities	4,173,943	4,096,363
Contingent consideration	3,970,931	1,595,273
Fair Value, Measurements, Recurring | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	132,510,610	19,114,444
Fair Value, Measurements, Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities	4,173,943	4,096,363
Contingent consideration	$ 3,970,931	$ 1,595,273