Insurance Liabilities (Reconciliation of Policyholder Account Balances) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Mar. 31, 2025
Policyholder Account Balance [Line Items]
Policyholder Account Balance	$ 86,379	$ 85,618
Rollforwards Total
Policyholder Account Balance [Line Items]
Policyholder Account Balance	75,552	74,122
Funding agreements classified as investment contracts
Policyholder Account Balance [Line Items]
Policyholder Account Balance	9,353	10,116
Institutional group annuities
Policyholder Account Balance [Line Items]
Policyholder Account Balance	595	401
Other investment contract liabilities
Policyholder Account Balance [Line Items]
Policyholder Account Balance	$ 879	$ 979

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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