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Acquisitions - Chasing Returns Ltd (Details) - USD ($) $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Aug. 03, 2021 | Sep. 30, 2021 | Sep. 30, 2020
Business Acquisition [Line Items] |  |  |
Goodwill |  | $ 58.1 | $ 54.7
Chasing Returns Limited |  |  |
Business Acquisition [Line Items] |  |  |
Total merger consideration | $ 6.0 |  |
Goodwill | 3.6 |  |
Chasing Returns Limited | Software programs/platforms |  |  |
Business Acquisition [Line Items] |  |  |
Finite-lived intangible assets acquired | $ 2.4 | $ 2.4 |

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