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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Loans and Leases - Schedule of Loans by Portfolio Segment (Details) - USD ($) $ in Millions	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 63,058		$ 62,565
Allowance for loan and lease losses	(777)	$ (814)	(815)	$ (823)	$ (821)	$ (773)
Net loans and leases	62,281		61,750
Commercial: \| Commercial, financial, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	34,401		33,428
Allowance for loan and lease losses	(334)	(347)	(345)	(352)	(344)	(339)
Commercial: \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	30,475		29,957
Commercial: \| Commercial and industrial \| Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Property, plant, and equipment and finance lease right-of-use asset	1,500		1,400
Commercial: \| Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	3,926		3,471
Commercial: \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,675		14,421
Allowance for loan and lease losses	(204)	(213)	(227)	(218)	(221)	(172)
Commercial: \| Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	154		174
Consumer:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,403		14,047
Consumer: \| HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,145		2,092
Consumer: \| Real estate installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,258		11,955
Consumer: \| Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	579		669
Allowance for loan and lease losses	$ (20)	$ (21)	$ (22)	$ (23)	$ (25)	$ (29)