Fair Value Measurements - Fair Value Measurements for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Acquisition related contingent consideration obligations	$ 1,595,273	$ 1,595,273	$ 173,621	$ 173,621
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	59,713,424	19,114,444
Derivative assets
Derivative liabilities	5,097,442	4,096,363
Acquisition related contingent consideration obligations	1,595,273	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	59,713,424	19,114,444
Derivative assets
Derivative liabilities
Acquisition related contingent consideration obligations
Fair Value, Measurements, Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents
Derivative assets
Derivative liabilities
Acquisition related contingent consideration obligations
Fair Value, Measurements, Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents
Derivative assets
Derivative liabilities	5,097,442	4,096,363
Acquisition related contingent consideration obligations	$ 1,595,273	$ 1,595,273