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Acquisitions (Details) - USD ($) $ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Aug. 31, 2021 | Aug. 06, 2021 | Dec. 31, 2023 | Dec. 31, 2022
Business Acquisition [Line Items] |  |  |  |
Goodwill and intangible assets, acquisitions |  |  | $ 11.0 | $ 8.0
Westpac Lenders Mortgage Insurance Limited |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Term of business exclusivity agreement | 10 years |  |  |
Somerset |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Goodwill and intangible assets, acquisitions |  | $ 350.1 |  |

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