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v3.20.4

Basis of Presentation and Consolidation and Accounting Standards Adopted (Details) $ in Millions |  | 3 Months Ended |
--- | --- | --- | ---
Oct. 01, 2020 USD ($) | Dec. 31, 2020 USD ($) country client | Dec. 31, 2019 USD ($) | Sep. 30, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Number of commercial and institutional clients (more than) | client |  | 32,000 |  |
Number retail clients (more than) | client |  | 330,000 |  |
Number of countries in which entity operates (more than) | country |  | 180 |  |
Selling and marketing |  | $ 8.8 | $ 1.4 |
Cumulative-effect adjustment, net of tax |  | 585.7 |  | $ 572.4
Income tax expense |  | $ 7.4 | $ 5.4 |
Cumulative Effect, Period of Adoption, Adjustment |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Cumulative-effect adjustment, net of tax | $ 6.2 |  |  |
Income tax expense | $ 2.0 |  |  |
Retail Segment |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |
Number of countries in which entity operates (more than) | country |  | 130 |  |

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