Loans, Leases, and Allowance for Credit Losses (Summary of Nonaccrual Loans) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	$ 91	$ 31
Amortized cost basis with allowance	131	118
Total amortized cost basis	222	149
Related allowance	43	35
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	23	21
Amortized cost basis with allowance	81	66
Total amortized cost basis	104	87
Related allowance	32	28
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	11	8
Amortized cost basis with allowance	71	55
Total amortized cost basis	82	63
Related allowance	30	27
Commercial | Leasing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	2
Total amortized cost basis	2
Related allowance	1
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	12	13
Amortized cost basis with allowance	8	11
Total amortized cost basis	20	24
Related allowance	1	1
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	59	0
Amortized cost basis with allowance	2	14
Total amortized cost basis	61	14
Related allowance	1	2
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	22
Amortized cost basis with allowance	0
Total amortized cost basis	22
Related allowance	0
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	37	0
Amortized cost basis with allowance	2	14
Total amortized cost basis	39	14
Related allowance	1	2
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	9	10
Amortized cost basis with allowance	48	38
Total amortized cost basis	57	48
Related allowance	10	5
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	1	1
Amortized cost basis with allowance	16	10
Total amortized cost basis	17	11
Related allowance	5	2
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	8	9
Amortized cost basis with allowance	32	28
Total amortized cost basis	40	37
Related allowance	$ 5	$ 3