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Summary of Significant Accounting Policies - Revenue Recognition and Concentrations of Credit Risk - Additional Information (Detail) - Customer
12 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Concentration Risk [Line Items]    
Number of customers with an account receivable balance of more than 10% of total accounts receivable 1 1
Accounts Receivable [Member] | Customer [Member]    
Concentration Risk [Line Items]    
Aggregate account receivable of more than 10% of total accounts receivable 35.00% 32.00%