Income from Investments - Net Impairment Losses Recognized in Earnings (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Net Investment Income [Line Items] | |||
| Net Impairment Losses Recognized in Earnings | $ (10.8) | $ (5.8) | $ (1.1) |
| Available for sale, debt securities, other than temporary impairment loss | 1.1 | 3.3 | 2.0 |
| Fixed Maturities: | |||
| Net Investment Income [Line Items] | |||
| Net Impairment Losses Recognized in Earnings | (10.8) | (4.8) | (0.1) |
| Equity Securities | |||
| Net Investment Income [Line Items] | |||
| Net Impairment Losses Recognized in Earnings | 0.0 | (0.4) | (0.5) |
| Real Estate | |||
| Net Investment Income [Line Items] | |||
| Net Impairment Losses Recognized in Earnings | (0.4) | 0.0 | |
| Net Impairment Losses Recognized in Earnings | 0.1 | ||
| Other Long-Term Investments | |||
| Net Investment Income [Line Items] | |||
| Net Impairment Losses Recognized in Earnings | $ (0.1) | $ (0.2) | $ (0.5) |