Loans, Leases, and Allowance for Credit Losses (Summary of Selected Information on TDRs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 123	$ 97
Percentage of total loans	0.20%	0.20%
Unfunded lending commitments on troubled debt restructuring	$ 3	$ 8
Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	4
Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	114	92
Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	2	0
Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	7	1
Commercial
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 33	$ 46
Percentage of total loans	0.10%	0.20%
Commercial | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 4
Commercial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	29	42
Commercial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	4	0
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 30	$ 36
Percentage of total loans	0.20%	0.20%
Commercial | Commercial and industrial | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Commercial | Commercial and industrial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	26	36
Commercial | Commercial and industrial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Commercial and industrial | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Commercial and industrial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	4	0
Commercial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 3	$ 10
Percentage of total loans	0.00%	0.10%
Commercial | Owner-occupied | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 4
Commercial | Owner-occupied | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	3	6
Commercial | Owner-occupied | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Owner-occupied | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial | Owner-occupied | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 84	$ 49
Percentage of total loans	0.60%	0.40%
Commercial real estate | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Commercial real estate | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	84	49
Commercial real estate | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Term
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 83	$ 49
Percentage of total loans	0.80%	0.50%
Commercial real estate | Term | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Commercial real estate | Term | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	83	49
Commercial real estate | Term | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Term | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Term | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Construction and land development
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 1	$ 0
Percentage of total loans	0.00%	0.00%
Commercial real estate | Construction and land development | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Commercial real estate | Construction and land development | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	1	0
Commercial real estate | Construction and land development | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Construction and land development | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Commercial real estate | Construction and land development | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 6	$ 2
Percentage of total loans	0.00%	0.00%
Consumer | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Consumer | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	1	1
Consumer | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	2	0
Consumer | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	3	1
Consumer | 1-4 family residential
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 4	$ 1
Percentage of total loans	0.00%	0.00%
Consumer | 1-4 family residential | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Consumer | 1-4 family residential | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | 1-4 family residential | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	2	0
Consumer | 1-4 family residential | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | 1-4 family residential | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	2	1
Consumer | Bankcard and other revolving plans
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 1
Percentage of total loans	0.00%	0.20%
Consumer | Bankcard and other revolving plans | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Consumer | Bankcard and other revolving plans | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	1
Consumer | Bankcard and other revolving plans | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Bankcard and other revolving plans | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Bankcard and other revolving plans | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Home equity credit line
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 1	$ 0
Percentage of total loans	0.00%	0.00%
Consumer | Home equity credit line | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Consumer | Home equity credit line | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Home equity credit line | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Home equity credit line | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Home equity credit line | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	1	0
Consumer | Other
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 1	$ 0
Percentage of total loans	0.80%	0.00%
Consumer | Other | Interest rate reduction
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0
Consumer | Other | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Amortized cost basis	1	0
Consumer | Other | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Other | Payment deferral
Financing Receivable, Modifications [Line Items]
Amortized cost basis	0	0
Consumer | Other | Multiple modification types
Financing Receivable, Modifications [Line Items]
Amortized cost basis	$ 0	$ 0