Loans, Leases, and Allowance for Credit Losses (Summary of Nonaccrual Loans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	$ 118	$ 183
Amortized cost basis with no allowance	31	88
Total amortized cost basis	149	271
Related allowance	35	48
Accrued interest receivable written off	13	17	$ 19
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	66	115
Amortized cost basis with no allowance	21	69
Total amortized cost basis	87	184
Related allowance	28	37
Accrued interest receivable written off	12	15	16
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	52	94
Amortized cost basis with no allowance	4	30
Total amortized cost basis	56	124
Related allowance	26	34
Commercial | PPP
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	3	1
Amortized cost basis with no allowance	4	2
Total amortized cost basis	7	3
Related allowance	1	0
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	11	20
Amortized cost basis with no allowance	13	37
Total amortized cost basis	24	57
Related allowance	1	3
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	14	14
Amortized cost basis with no allowance	0	6
Total amortized cost basis	14	20
Related allowance	2	3
Accrued interest receivable written off	1	2	2
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	14	14
Amortized cost basis with no allowance	0	6
Total amortized cost basis	14	20
Related allowance	2	3
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	38	54
Amortized cost basis with no allowance	10	13
Total amortized cost basis	48	67
Related allowance	5	8
Accrued interest receivable written off	0	0	$ 1
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	10	10
Amortized cost basis with no allowance	1	4
Total amortized cost basis	11	14
Related allowance	2	2
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance	28	43
Amortized cost basis with no allowance	9	9
Total amortized cost basis	37	52
Related allowance	$ 3	5
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with allowance		1
Amortized cost basis with no allowance		0
Total amortized cost basis		1
Related allowance		$ 1