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Business Combinations - Acquisition related expense (Details) - Columbia Banking Systems and Pacific Premier Bancorp Merger - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Business Combination [Line Items]
Personnel	$ 39	$ 2	$ 53	$ 8
Premises and equipment	17	0	17	1
Legal and professional	26	0	29	0
Other	1	0	2	0
Total acquisition-related expenses	$ 83	$ 2	$ 101	$ 9

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