Derivative And Credit-Related Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Maximum estimated exposure to credit risk participation agreements assuming 100% default		$ 2	$ 0
Notional/Contract Amount	[1]	21,890	20,545
Fair Value of Gross Derivative Assets		267	192
Fair Value of Gross Derivative Liabilities		364	190
Derivative assets, Netting adjustment - Offsetting derivative liabilities		(42)	(49)
Derivative liabilities, Netting adjustment - Offsetting derivative assets		(42)	(49)
Derivative assets, Netting adjustment - Cash collateral received		(6)	(1)
Derivative liabilities, Netting adjustment, Cash collateral posted		(173)	(39)
Net derivative assets included in the consolidated balance sheets	[2]	219	142
Net derivative liabilities included in the consolidated balance sheets	[2]	149	102
Derivative asset, securities pledged as collateral		(10)	(3)
Derivative liability, securities pledged as collateral		(8)	(24)
Net derivative assets after deducting amounts not offset in the consolidated balance sheets		209	139
Net derivative liabilities after deducting amounts not offset in the consolidated balance sheets		141	78
Credit valuation adjustments for counterparty credit risk		3	4
Risk management purposes
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,953	2,425
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		3	4
Risk management purposes | Derivatives designated as hedging instruments | Fair Value Hedging | Interest rate swap
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,625	1,775
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		3	2
Risk management purposes | Derivatives used as economic hedges | Foreign exchange spot, forwards and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	328	650
Fair Value of Gross Derivative Assets		1	0
Fair Value of Gross Derivative Liabilities		0	2
Customer-initiated and other activities
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	18,937	18,120
Fair Value of Gross Derivative Assets		266	192
Fair Value of Gross Derivative Liabilities		361	186
Customer-initiated and other activities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	14,368	14,389
Fair Value of Gross Derivative Assets		31	57
Fair Value of Gross Derivative Liabilities		128	57
Customer-initiated and other activities | Interest rate caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	799	635
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]
Notional/Contract Amount	[1]	799	635
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]
Notional/Contract Amount	[1]	12,770	13,119
Fair Value of Gross Derivative Assets		29	57
Fair Value of Gross Derivative Liabilities		126	57
Customer-initiated and other activities | Energy contracts
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,595	1,847
Fair Value of Gross Derivative Assets		219	93
Fair Value of Gross Derivative Liabilities		219	91
Customer-initiated and other activities | Energy caps and floors written
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	258	164
Fair Value of Gross Derivative Assets		0	0
Fair Value of Gross Derivative Liabilities		21	11
Customer-initiated and other activities | Energy caps and floors purchased
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	258	164
Fair Value of Gross Derivative Assets		21	11
Fair Value of Gross Derivative Liabilities		0	0
Customer-initiated and other activities | Energy swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	2,079	1,519
Fair Value of Gross Derivative Assets		198	82
Fair Value of Gross Derivative Liabilities		198	80
Customer-initiated and other activities | Foreign exchange spot, options and swaps
Derivatives, Fair Value [Line Items]
Notional/Contract Amount	[1]	1,974	1,884
Fair Value of Gross Derivative Assets		16	42
Fair Value of Gross Derivative Liabilities		$ 14	$ 38

[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 $4 million at September 30, 2018 and December 31, 2017, respectively.