Insurance Liabilities (Future Policy Benefits - Reconciliation) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	$ 32,387	$ 29,924
Liabilities reported in the preceding rollforward tables
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	22,005	19,188
Long-term care insurance (1)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	5,514	5,276
ULSG liabilities, including liability for profits followed by losses
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	1,202	1,966
Participating whole life insurance (2)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	2,923	2,802
Deferred profit liabilities
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	431	455
Other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	$ 312	$ 237