Insurance Liabilities (Reconciliation of Policyholder Account Balances) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Policyholder Account Balance [Line Items]
Policyholder Account Balance	$ 86,836	$ 77,474
Rollforwards Total
Policyholder Account Balance [Line Items]
Policyholder Account Balance	73,996	65,452
Funding agreements classified as investment contracts
Policyholder Account Balance [Line Items]
Policyholder Account Balance	11,561	11,052
Institutional group annuities
Policyholder Account Balance [Line Items]
Policyholder Account Balance	363	0
Other investment contract liabilities
Policyholder Account Balance [Line Items]
Policyholder Account Balance	$ 916	$ 970