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Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Aug. 31, 2025	Dec. 31, 2024
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,481,000,000			$ 1,481,000,000			$ 1,029,000,000
Finite-Lived Intangible Asset, Useful Life	10 years			10 years
Goodwill and Intangible Asset Impairment			$ 0	$ 0
Intangible amortization	$ 31,000,000	$ 29,000,000		$ 85,000,000	$ 90,000,000
Columbia Banking Systems and Pacific Premier Bancorp Merger
Finite-Lived Intangible Assets [Line Items]
Goodwill						$ 452,000,000
Finite-Lived Intangible Asset, Useful Life						10 years
Columbia Banking Systems and Pacific Premier Bancorp Merger | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets Acquired	$ 355,000,000

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