Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	$ 34,474	$ 30,134
Fair Value of Gross Derivative Assets		825	317
Fair Value of Gross Derivative Liabilities		287	141
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(72)	(63)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(72)	(63)
Derivative assets, Netting adjustment - Cash collateral received		(118)	(11)
Derivative liabilities, Netting adjustment, Cash collateral posted		(36)	(12)
Net derivative assets included in the consolidated balance sheets	[2]	635	243
Net derivative liabilities included in the consolidated balance sheets	[2]	179	66
Derivative asset, securities pledged as collateral		0	0
Derivative liability, securities pledged as collateral		(48)	(21)
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		635	243
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		131	45
Credit valuation adjustments for counterparty credit risk		31	9
Risk management purposes
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	8,528	8,205
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		2	2
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	4,550
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]	5,550	3,325
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]	328	330
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		2	2
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	25,946	21,929
Fair Value of Gross Derivative Assets		825	317
Fair Value of Gross Derivative Liabilities		285	139
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	21,753	17,827
Fair Value of Gross Derivative Assets		601	211
Fair Value of Gross Derivative Liabilities		68	39
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	745	671
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	745	671
Fair Value of Gross Derivative Assets		0	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]	20,263	16,485
Fair Value of Gross Derivative Assets		601	211
Fair Value of Gross Derivative Liabilities		68	39
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	3,020	3,089
Fair Value of Gross Derivative Assets		214	96
Fair Value of Gross Derivative Liabilities		209	92
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	447	477
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		36	23
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	447	477
Fair Value of Gross Derivative Assets		36	23
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	2,126	2,135
Fair Value of Gross Derivative Assets		177	73
Fair Value of Gross Derivative Liabilities		173	69
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	1,173	1,013
Fair Value of Gross Derivative Assets		10	10
Fair Value of Gross Derivative Liabilities		$ 8	$ 8

[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 $31 million and $9 million at September 30, 2020 and December 31, 2019, respectively.