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Segment and Revenue Information - Narrative (Details)
12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Customer Concentration Risk | Sales Revenue, Segment | Three Significant Customers      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Concentration risk percentage 70.00% 57.00% 55.00%