v3.21.2
Enterprise-wide Disclosures and Concentration of Business - Additional Information (Detail) - Net Operating Revenue
12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Customer Concentration Risk | Customer One      
Concentration Risk [Line Items]      
Concentration risk, percentage 11.00% 11.00%  
Customer Concentration Risk | Customer Two      
Concentration Risk [Line Items]      
Concentration risk, percentage   10.00%  
U.S. | Geographic Concentration Risk      
Concentration Risk [Line Items]      
Concentration risk, percentage 46.00% 46.00% 45.00%