Loans And Allowance For Credit Losses (Summary Of Changes In The Allowance For Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period				$ 518				$ 567	$ 518	$ 567
Provision for loan losses	$ 7	$ (11)	$ 5	(40)	$ (11)	$ 5	$ 7	23	(39)	24	$ 93
Gross loan and lease charge-offs									69	144
Recoveries									85	71
Net loan and lease charge-offs									(16)	73
Balance at end of period	495				518				495	518	567
Balance at beginning of period				58				65	58	65
Provision charged (credited) to earnings									(1)	(7)	(10)
Balance at end of period	57				58				57	58	65
Allowance for loan losses	495			518	518			567	518	567	567	$ 495	$ 518
Reserve for unfunded lending commitments	57			58	58			65	58	65	65	57	58
Total allowance for credit losses												552	576
Commercial [Member]
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period				371				420	371	420
Provision for loan losses									(62)	23
Gross loan and lease charge-offs									46	118
Recoveries									68	46
Net loan and lease charge-offs									(22)	72
Balance at end of period	331				371				331	371	420
Balance at beginning of period				48				54	48	54
Provision charged (credited) to earnings									(8)	(6)
Balance at end of period	40				48				40	48	54
Allowance for loan losses	331			371	371			420	371	420	420	331	371
Reserve for unfunded lending commitments	40			48	48			54	48	54	54	40	48
Total allowance for credit losses												371	419
Commercial Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period				103				116	103	116
Provision for loan losses									3	(18)
Gross loan and lease charge-offs									5	9
Recoveries									9	14
Net loan and lease charge-offs									(4)	(5)
Balance at end of period	110				103				110	103	116
Balance at beginning of period				10				11	10	11
Provision charged (credited) to earnings									7	(1)
Balance at end of period	17				10				17	10	11
Allowance for loan losses	110			103	103			116	103	116	116	110	103
Reserve for unfunded lending commitments	17			10	10			11	10	11	11	17	10
Total allowance for credit losses												127	113
Consumer [Member]
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period				44				31	44	31
Provision for loan losses									20	19
Gross loan and lease charge-offs									18	17
Recoveries									8	11
Net loan and lease charge-offs									10	6
Balance at end of period	54				44				54	44	31
Balance at beginning of period				0				0	0	0
Provision charged (credited) to earnings									0	0
Balance at end of period	0				0				0	0	0
Allowance for loan losses	54			44	44			31	44	31	31	54	44
Reserve for unfunded lending commitments	$ 0			$ 0	$ 0			$ 0	$ 0	$ 0	$ 0	0	0
Total allowance for credit losses												$ 54	$ 44