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Business Combinations - PCD Loans (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Aug. 31, 2025	Sep. 30, 2025	Sep. 30, 2025
Business Combination [Line Items]
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		$ (5)	$ (5)
Columbia Banking Systems and Pacific Premier Bancorp Merger
Business Combination [Line Items]
Principal of PCD loans acquired	$ 463
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	(5)
Non-credit discount on PCD loans	(54)
Fair value of PCD loans	$ 404

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