Loans And Allowance For Credit Losses (Summary Of Changes In The Allowance For Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	$ (20)	$ (5)	$ (22)	$ 35
Allowance for Loan and Lease Losses, Write-offs	(23)	(13)	(35)	(39)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	497	473	495	518
Net loan and lease charge-offs	14	(12)	14	(7)
Balance at end of period	60	58	60	58
Allowance for loan losses	503	473	503	518	$ 503	$ 497	$ 495	$ 490	$ 473	$ 518
Reserve for unfunded lending commitments	60	58	60	58	60	59	57	58	51	58
Allowance for loan and lease losses and reserve for unfunded lending commitments					563			548
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	9	25	21	46
Provision for Unfunded Lending Commitments (decrease)	1	7	3	0
Balance at end of period	503	490	503	490
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	23	(18)	(22)	58
Allowance for Loan and Lease Losses, Write-offs	(19)	(10)	(27)	(30)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	328	329	331	371
Net loan and lease charge-offs	13	(10)	15	(8)
Balance at end of period	41	43	41	43
Allowance for loan losses	328	329	338	371	338	328	331	321	329	371
Reserve for unfunded lending commitments	41	43	41	43	41	42	40	43	40	48
Allowance for loan and lease losses and reserve for unfunded lending commitments					379			364
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	6	20	12	38
Provision for Unfunded Lending Commitments (decrease)	(1)	3	1	(5)
Balance at end of period	338	321	338	321
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	(1)	(15)	(2)	(14)
Allowance for Loan and Lease Losses, Write-offs	0	0	(1)	0
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	113	104	110	103
Net loan and lease charge-offs	0	(3)	(2)	(5)
Balance at end of period	19	15	19	15
Allowance for loan losses	113	104	114	103	114	113	110	122	104	103
Reserve for unfunded lending commitments	19	15	19	15	19	17	17	15	11	10
Allowance for loan and lease losses and reserve for unfunded lending commitments					133			137
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	0	3	3	5
Provision for Unfunded Lending Commitments (decrease)	2	4	2	5
Balance at end of period	114	122	114	122
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	4	(8)	2	(9)
Allowance for Loan and Lease Losses, Write-offs	(4)	(3)	(7)	(9)
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	56	40	54	44
Net loan and lease charge-offs	1	1	1	6
Balance at end of period	0	0	0	0
Allowance for loan losses	56	40	51	47	51	56	54	47	40	44
Reserve for unfunded lending commitments	0	0	0	0	0	$ 0	$ 0	0	$ 0	$ 0
Allowance for loan and lease losses and reserve for unfunded lending commitments					$ 51			$ 47
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	3	2	6	3
Provision for Unfunded Lending Commitments (decrease)	0	0	0	0
Balance at end of period	$ 51	$ 47	$ 51	$ 47