Basis of Presentation and Accounting Policies Basis of Presentation and Accounting Policies (Narrative) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2022 USD ($) segments	Dec. 31, 2021 USD ($)
Federal Home Loan Bank Stock		$ 138	$ 7
Federal Reserve Bank Stock		85	85
Net Deferred Income on Originated Loans		$ 118	102
Delinquency Status, Period of Unpaid Scheduled Monthly Payment		30 days
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, after Accumulated Amortization		$ 32	21
Hosting Arrangement, Service Contract, Implementation Cost, Capitalized, Accumulated Amortization		$ 3	3
Number of Reporting Units | segments		3
Derivative, Notional Amount	[1]	$ 67,665	$ 41,638
Defined Benefit Plan Investment Gain Loss Amortization Adjustment, Allowable Percentage		10.00%
Defined Benefit Plan Actuarial Gain Loss Amortization Adjustment, Allowable Percentage		10.00%
Defined Benefit Plan Market-related Value Plan Assets, Amortization Period		5 years
Premises the Corporation owns | Minimum
Premises and Equipment, Useful Life		3 years
Premises the Corporation owns | Maximum
Premises and Equipment, Useful Life		33 years
Furniture and equipment | Minimum
Premises and Equipment, Useful Life		3 years
Furniture and equipment | Maximum
Premises and Equipment, Useful Life		8 years
Leasehold improvements | Maximum
Premises and Equipment, Useful Life		10 years
Software
Premises and Equipment, Useful Life		5 years
Retail loans | Commercial mortgage
Past Due Period Residential Mortgage And Home Equity Loans Placed On Nonaccrual Status		90 days
Past Due Threshold For Charge-Off		180 days
Commercial borrower | Business loans
Past Due Period Business Loans Placed On Nonaccrual Status		90 days
Consumer borrower | Retail loans | Home equity
Maximum Past Due Status Junior Lien Home Equity Placed On Nonaccrual Status		90 days
Consumer borrower | Retail loans | Other consumer
Past Due Threshold For Charge-Off		120 days
Threshold, Days Past Due, Other Consumer Placed On Nonaccrual Status		90 days
Swaps - fair value - receive fixed/pay floating | Short-Cut Method | Not Designated as Hedging Instrument [Member] | Interest rate swap
Derivative, Notional Amount		$ 2,600

[1] Notional or contractual amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected on the Consolidated Balance Sheets.