Loans and Allowance for Loan Losses - Schedule of Current, Accruing Past Due, and Non-Accrual Loans by Portfolio Class (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	$ 89,808	$ 39,154
Non-accrual with an ALL	231	103
Non-accrual without an ALL	202	30
Accrued interest receivable	365	151
Deferred loan fees	351	314
Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	52,063	22,296
Non-accrual with an ALL	82	38
Non-accrual without an ALL	128	16
Total commercial and industrial \| Commercial, financial and agricultural
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	37,456	16,549
Non-accrual with an ALL	58	35
Non-accrual without an ALL	104	13
Total commercial and industrial \| Owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	14,607	5,747
Non-accrual with an ALL	24	3
Non-accrual without an ALL	24	3
Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	24,037	11,356
Non-accrual with an ALL	52	36
Non-accrual without an ALL	74	14
Total commercial real estate \| Investment properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	21,064	9,496
Non-accrual with an ALL	48	34
Non-accrual without an ALL	74	14
Total commercial real estate \| 1-4 family properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,995	1,284
Non-accrual with an ALL	4	2
Non-accrual without an ALL	0	0
Total commercial real estate \| Land and development
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	978	576
Non-accrual with an ALL	0	0
Non-accrual without an ALL	0	0
Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	13,708	5,502
Non-accrual with an ALL	97	29
Non-accrual without an ALL	0	0
Total consumer \| Consumer mortgages
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,701	3,456
Non-accrual with an ALL	72	23
Non-accrual without an ALL	0	0
Total consumer \| Home equity
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3,001	1,374
Non-accrual with an ALL	19	6
Non-accrual without an ALL	0	0
Total consumer \| Credit cards
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	252	53
Non-accrual with an ALL	0	0
Non-accrual without an ALL	0	0
Total consumer \| Other consumer loans
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,754	619
Non-accrual with an ALL	6	0
Non-accrual without an ALL	0	0
Current
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	89,245	38,964
Current \| Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	51,797	22,216
Current \| Total commercial and industrial \| Commercial, financial and agricultural
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	37,255	16,478
Current \| Total commercial and industrial \| Owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	14,542	5,738
Current \| Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	23,896	11,304
Current \| Total commercial real estate \| Investment properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	20,931	9,448
Current \| Total commercial real estate \| 1-4 family properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,988	1,280
Current \| Total commercial real estate \| Land and development
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	977	576
Current \| Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	13,552	5,444
Current \| Total consumer \| Consumer mortgages
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8,608	3,417
Current \| Total consumer \| Home equity
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	2,964	1,360
Current \| Total consumer \| Credit cards
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	247	51
Current \| Total consumer \| Other consumer loans
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1,733	616
Accruing 30-89 Days Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	122	54
Accruing 30-89 Days Past Due \| Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	51	24
Accruing 30-89 Days Past Due \| Total commercial and industrial \| Commercial, financial and agricultural
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	34	21
Accruing 30-89 Days Past Due \| Total commercial and industrial \| Owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	17	3
Accruing 30-89 Days Past Due \| Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	15	2
Accruing 30-89 Days Past Due \| Total commercial real estate \| Investment properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	11	0
Accruing 30-89 Days Past Due \| Total commercial real estate \| 1-4 family properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3	2
Accruing 30-89 Days Past Due \| Total commercial real estate \| Land and development
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1	0
Accruing 30-89 Days Past Due \| Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	56	28
Accruing 30-89 Days Past Due \| Total consumer \| Consumer mortgages
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	21	16
Accruing 30-89 Days Past Due \| Total consumer \| Home equity
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	18	8
Accruing 30-89 Days Past Due \| Total consumer \| Credit cards
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	2	1
Accruing 30-89 Days Past Due \| Total consumer \| Other consumer loans
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	15	3
Accruing 90 Days or Greater Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	8	3
Accruing 90 Days or Greater Past Due \| Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5	2
Accruing 90 Days or Greater Past Due \| Total commercial and industrial \| Commercial, financial and agricultural
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5	2
Accruing 90 Days or Greater Past Due \| Total commercial and industrial \| Owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total commercial real estate \| Investment properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total commercial real estate \| 1-4 family properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total commercial real estate \| Land and development
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3	1
Accruing 90 Days or Greater Past Due \| Total consumer \| Consumer mortgages
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total consumer \| Home equity
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due \| Total consumer \| Credit cards
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3	1
Accruing 90 Days or Greater Past Due \| Total consumer \| Other consumer loans
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	0	0
Total Accruing Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	130	57
Total Accruing Past Due \| Total commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	56	26
Total Accruing Past Due \| Total commercial and industrial \| Commercial, financial and agricultural
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	39	23
Total Accruing Past Due \| Total commercial and industrial \| Owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	17	3
Total Accruing Past Due \| Total commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	15	2
Total Accruing Past Due \| Total commercial real estate \| Investment properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	11	0
Total Accruing Past Due \| Total commercial real estate \| 1-4 family properties
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	3	2
Total Accruing Past Due \| Total commercial real estate \| Land and development
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	1	0
Total Accruing Past Due \| Total consumer
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	59	29
Total Accruing Past Due \| Total consumer \| Consumer mortgages
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	21	16
Total Accruing Past Due \| Total consumer \| Home equity
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	18	8
Total Accruing Past Due \| Total consumer \| Credit cards
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	5	2
Total Accruing Past Due \| Total consumer \| Other consumer loans
Financing Receivable, Nonaccrual [Line Items]
Loans, net of deferred fees and costs	$ 15	$ 3

Amount, after allowance for credit loss, of accrued interest on financing receivable.

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