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Future policy benefits (Weighted average interest rates) (Details) - Segment Life [Member] | Sep. 30, 2025 | Sep. 30, 2024
--- | --- | ---
Term Life Insurance |  |
Liability for Future Policy Benefit, Activity [Line Items] |  |
Interest Accretion Rate | 3.00% | 3.00%
Current Discount Rate | 5.70% | 5.20%
Whole Life Insurance |  |
Liability for Future Policy Benefit, Activity [Line Items] |  |
Interest Accretion Rate | 3.40% | 3.20%
Current Discount Rate | 4.10% | 4.10%
Accident and Health Insurance Product Line [Member] |  |
Liability for Future Policy Benefit, Activity [Line Items] |  |
Interest Accretion Rate | 4.20% | 3.80%
Current Discount Rate | 5.80% | 5.80%
Insurance, Other |  |
Liability for Future Policy Benefit, Activity [Line Items] |  |
Interest Accretion Rate | 3.30% | 2.70%
Current Discount Rate | 3.50% | 3.80%

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