Derivative Instruments And Hedging Activities (Schedule Of Notional Amounts And Recorded Gross Fair Values And Related Gain (Loss) Of Derivative Instruments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Total derivatives, Notional amount	$ 6,824	$ 6,209
Amount of derivative gain (loss), recognized in OCI	(8)	8
Amount of derivative gain (loss), Reclassified from AOCI to interest income	4	11
Derivatives instruments, Noninterest income (expense)	27	26
Derivatives designated as hedging instruments, Offset to interest expense	0	0
Other Assets [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	38	64
Other Liabilities [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	40	59
Derivatives Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Total derivatives, Notional amount	1,138	1,388
Amount of derivative gain (loss), recognized in OCI	(8)	8
Amount of derivative gain (loss), Reclassified from AOCI to interest income	4	11
Derivatives Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Assets [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	0	2
Derivatives Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Liabilities [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	0	1
Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Total derivatives, Notional amount	5,686	4,821
Derivatives Not Designated As Hedging Instruments [Member] | Other Assets [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	38	62
Derivatives Not Designated As Hedging Instruments [Member] | Other Liabilities [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	40	58
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Total derivatives, Notional amount	223	235
Derivatives instruments, Noninterest income (expense)	(1)	1
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Assets [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	1	2
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Liabilities [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	0	0
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps For Customers [Member]
Derivative [Line Items]
Total derivatives, Notional amount	4,550	4,162
Derivatives instruments, Noninterest income (expense)	11	14
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps For Customers [Member] | Other Assets [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	28	49
Derivatives Not Designated As Hedging Instruments [Member] | Interest Rate Swaps For Customers [Member] | Other Liabilities [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	33	49
Derivatives Not Designated As Hedging Instruments [Member] | Foreign Exchange [Member]
Derivative [Line Items]
Total derivatives, Notional amount	913	424
Derivatives instruments, Noninterest income (expense)	17	11
Derivatives Not Designated As Hedging Instruments [Member] | Foreign Exchange [Member] | Other Assets [Member]
Derivative [Line Items]
Derivatives hedging instruments, assets	9	11
Derivatives Not Designated As Hedging Instruments [Member] | Foreign Exchange [Member] | Other Liabilities [Member]
Derivative [Line Items]
Derivatives hedging instruments, liabilities	$ 7	$ 9