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Commitments, Contingencies, Guarantees and Others - Other Contingencies (Details) - USD ($) $ in Millions	3 Months Ended	11 Months Ended
	Mar. 31, 2025	Sep. 30, 2024
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 300
FDIC Special Assessment
Loss Contingencies [Line Items]
Operating expenses	328	$ 289
Loss contingency, estimate of possible loss	$ 200

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- Definition

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.

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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