Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
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| Statement of Comprehensive Income [Abstract] | ||||
| Change in unrealized losses on securities, tax | $ 73.7 | $ (18.2) | $ 91.2 | $ (58.5) |
| Change in unrealized gains (losses) on derivative transactions, tax | 3.6 | 0.5 | 4.3 | 0.0 |
| Change in foreign currency translation, tax | (0.3) | (0.5) | (0.7) | (3.4) |
| Change in pension and postretirement unrecognized net periodic benefit cost, tax | $ (0.2) | $ (0.1) | $ (0.5) | $ (0.7) |
| X | ||||||||||
- Definition Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| 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
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| 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
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| 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
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| X | ||||||||||
- References No definition available.
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