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v3.25.3

Investments - Net Investment Income (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Net Investment Income [Line Items] |  |  |  |
Total net investment income | $ 119.6 | $ 113.0 | $ 346.3 | $ 326.8
Investment Portfolio |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment expenses | (3.2) | (4.0) | (9.1) | (9.8)
Total net investment income | 96.4 | 87.2 | 273.6 | 249.8
Deposit Asset on Reinsurance |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Total net investment income | 23.2 | 25.8 | 72.7 | 77.0
Fixed maturity securities | Investment Portfolio |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Net investment income | 71.5 | 69.4 | 202.5 | 211.8
Equity securities | Investment Portfolio |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Net investment income | 0.9 | 1.3 | 2.9 | 3.9
Limited partnership interests | Investment Portfolio |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Net investment income | 21.4 | 14.5 | 60.9 | 28.9
Short-term and other investments | Investment Portfolio |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Net investment income | $ 5.8 | $ 6.0 | $ 16.4 | $ 15.0

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