Income Taxes - Comprehensive Income Tax Benefit and Expense (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Income Tax Disclosure [Abstract] | |||
| Income Tax Expense (Benefit) | $ 28.1 | $ 76.0 | $ (74.8) |
| Unrealized Appreciation (Depreciation) on Securities | (34.0) | 42.2 | (50.3) |
| Tax Effects from Postretirement Benefit Plans | 0.4 | 0.3 | (12.4) |
| Tax Effects on changes in Discount Rate for Life Reserves | 7.8 | (58.3) | 21.2 |
| Tax Effects from Cash Flow Hedge | 0.2 | 0.8 | 0.0 |
| Comprehensive Income (Loss), Tax | $ 53.7 | $ 91.0 | $ (33.3) |
| X | ||||||||||
- Definition Comprehensive Income (Loss), Tax No definition available.
|
| X | ||||||||||
- Definition Other Comprehensive (Income) Loss, Changes In Discount Rate for Life Reserves, after Reclassification Adjustment, Tax No definition available.
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount, after adjustment, of tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount, after reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|