Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	$ 37,684	$ 35,185
Fair Value of Gross Derivative Assets		955	700
Fair Value of Gross Derivative Liabilities		647	229
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(46)	(83)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(46)	(83)
Derivative assets, Netting adjustment - Cash collateral received		(15)	(17)
Derivative liabilities, Netting adjustment, Cash collateral posted		(539)	(48)
Net derivative assets included in the Consolidated Balance Sheets	[2]	894	600
Net derivative liabilities included in the Consolidated Balance Sheets	[2]	62	98
Derivative asset, securities pledged as collateral		0	0
Derivative liability, securities pledged as collateral		(39)	(42)
Net derivative assets after deducting amounts not offset in the Consolidated Balance Sheets		894	600
Net derivative liabilities after deducting amounts not offset in the Consolidated Balance Sheets		23	56
Credit valuation adjustments for counterparty credit risk		15	27
Risk management purposes
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	8,390	8,642
Fair Value of Gross Derivative Assets		1	1
Fair Value of Gross Derivative Liabilities		0	4
Risk management purposes | Derivatives designated as hedging instruments | Swaps - fair value - receive fixed/pay floating | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	2,650	2,650
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives designated as hedging instruments | Swaps - cash flow - receive fixed/pay floating rate | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	5,250	5,550
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Risk management purposes | Derivatives used as economic hedges | Foreign exchange spot, forwards and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	490	442
Fair Value of Gross Derivative Assets		1	1
Fair Value of Gross Derivative Liabilities		0	4
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	29,294	26,543
Fair Value of Gross Derivative Assets		954	699
Fair Value of Gross Derivative Liabilities		647	225
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	22,673	21,521
Fair Value of Gross Derivative Assets		367	531
Fair Value of Gross Derivative Liabilities		67	61
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	838	869
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		2	0
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	838	869
Fair Value of Gross Derivative Assets		2	0
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	20,997	19,783
Fair Value of Gross Derivative Assets		365	531
Fair Value of Gross Derivative Liabilities		65	61
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	4,710	3,121
Fair Value of Gross Derivative Assets		573	151
Fair Value of Gross Derivative Liabilities		570	149
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	728	503
Fair Value of Gross Derivative Assets		1	1
Fair Value of Gross Derivative Liabilities		96	33
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	728	503
Fair Value of Gross Derivative Assets		96	33
Fair Value of Gross Derivative Liabilities		1	1
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	3,254	2,115
Fair Value of Gross Derivative Assets		476	117
Fair Value of Gross Derivative Liabilities		473	115
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	1,911	1,901
Fair Value of Gross Derivative Assets		14	17
Fair Value of Gross Derivative Liabilities		$ 10	$ 15

[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 in the Consolidated Balance Sheets.

[2] Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $15 million and $27 million at June 30, 2021 and December 31, 2020, respectively.