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Loans and Leases - Schedule of Loans and Leases by Portfolio Segment (Details) - USD ($) $ in Millions	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 65,330		$ 64,156
Allowance for loan and lease losses	(709)	$ (730)	(738)	$ (814)	$ (822)	$ (815)
Net loans and leases	64,621		63,418
Commercial \| Commercial, financial, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	37,296		35,905
Allowance for loan and lease losses	(350)	(353)	(335)	(347)	(345)	(345)
Commercial \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	32,537		31,202
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		1,500
Commercial \| Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,759		4,703
Commercial \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,595		13,563
Allowance for loan and lease losses	(150)	(156)	(177)	(213)	(225)	(227)
Commercial \| Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	153		143
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,869		14,108
Consumer \| HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,163		2,164
Consumer \| Real estate installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	11,706		11,944
Consumer \| Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	570		580
Allowance for loan and lease losses	$ (19)	$ (20)	$ (20)	$ (21)	$ (22)	$ (22)