Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	$ 23,660	$ 21,557
Fair Value of Gross Derivative Assets		223	275
Fair Value of Gross Derivative Liabilities		149	269
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(65)	(45)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(65)	(45)
Derivative assets, Netting adjustment - Cash collateral received		(18)	(174)
Derivative liabilities, Netting adjustment, Cash collateral posted		(18)	(1)
Net derivative assets included in the consolidated balance sheets	[2]	140	56
Net derivative liabilities included in the consolidated balance sheets	[2]	66	223
Derivative asset, securities pledged as collateral		0	(1)
Derivative liability, securities pledged as collateral		(10)	0
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		140	55
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		56	223
Credit valuation adjustments for counterparty credit risk		3	2
Risk management purposes
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	4,157	2,927
Fair Value of Gross Derivative Assets		2	1
Fair Value of Gross Derivative Liabilities		2	3
Risk management purposes | Derivatives designated as hedging instruments | Fair Value Hedging | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,975	2,625
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 - cash flow - receive fixed/pay floating rate | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	800	0
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]
Notional/Contract Amount	[1]	382	302
Fair Value of Gross Derivative Assets		2	1
Fair Value of Gross Derivative Liabilities		0	1
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	19,503	18,630
Fair Value of Gross Derivative Assets		221	274
Fair Value of Gross Derivative Liabilities		147	266
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	15,429	14,885
Fair Value of Gross Derivative Assets		112	67
Fair Value of Gross Derivative Liabilities		45	68
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	908	885
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		1	1
Customer-initiated and other activities | Interest rate caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	908	885
Fair Value of Gross Derivative Assets		1	1
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	13,613	13,115
Fair Value of Gross Derivative Assets		111	66
Fair Value of Gross Derivative Liabilities		44	67
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,785	2,650
Fair Value of Gross Derivative Assets		96	189
Fair Value of Gross Derivative Liabilities		93	186
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	414	278
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		21	26
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	414	278
Fair Value of Gross Derivative Assets		21	26
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,957	2,094
Fair Value of Gross Derivative Assets		75	163
Fair Value of Gross Derivative Liabilities		72	160
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,289	1,095
Fair Value of Gross Derivative Assets		13	18
Fair Value of Gross Derivative Liabilities		$ 9	$ 12

[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 $3 million and $2 million at March 31, 2019 and December 31, 2018, respectively.