VARIABLE INTEREST ENTITIES, Primary Beneficiary - Aggregate Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Sep. 30, 2025
Variable interest entity, consolidated, aggregate assets and liabilities [Abstract]
Aggregate assets	$ 91,944	$ 88,230
Aggregate liabilities	79,334	75,726
Variable Interest Entity, Primary Beneficiary
Variable interest entity, consolidated, aggregate assets and liabilities [Abstract]
Aggregate assets	112	93
Aggregate liabilities	51	39
Variable Interest Entity, Primary Beneficiary \| LIHTC funds
Variable interest entity, consolidated, aggregate assets and liabilities [Abstract]
Aggregate assets	81	74
Aggregate liabilities	20	20
Variable Interest Entity, Primary Beneficiary \| Restricted Stock Trust Fund
Variable interest entity, consolidated, aggregate assets and liabilities [Abstract]
Aggregate assets	31	19
Aggregate liabilities	$ 31	$ 19

Amount of asset recognized for present right to economic benefit.

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+ Details

- Definition

Amount of liability recognized for present obligation requiring transfer or otherwise providing economic benefit to others.

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+ Details