Loans And Allowance For Credit Losses (Summary Of Changes In The Allowance For Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 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	$ (2)	$ 40
Allowance for Loan and Lease Losses, Write-offs	12	26
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	495	518
Allowance for Loan and Lease Losses, Adjustments, Other	0	5
Balance at end of period	59	51
Allowance for loan losses	495	518	$ 497	$ 495	$ 473	$ 518
Reserve for unfunded lending commitments	59	51	59	57	51	58
Allowance for loan and lease losses and reserve for unfunded lending commitments			556		524
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	12	21
Provision for Unfunded Lending Commitments (decrease)	2	(7)
Balance at end of period	497	473
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	1	40
Allowance for Loan and Lease Losses, Write-offs	8	20
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	331	371
Allowance for Loan and Lease Losses, Adjustments, Other	2	2
Balance at end of period	42	40
Allowance for loan losses	331	371	328	331	329	371
Reserve for unfunded lending commitments	42	40	42	40	40	48
Allowance for loan and lease losses and reserve for unfunded lending commitments			370		369
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	6	18
Provision for Unfunded Lending Commitments (decrease)	2	(8)
Balance at end of period	328	329
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)	1
Allowance for Loan and Lease Losses, Write-offs	1	0
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	110	103
Allowance for Loan and Lease Losses, Adjustments, Other	(2)	(2)
Balance at end of period	17	11
Allowance for loan losses	110	103	113	110	104	103
Reserve for unfunded lending commitments	17	11	17	17	11	10
Allowance for loan and lease losses and reserve for unfunded lending commitments			130		115
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	3	2
Provision for Unfunded Lending Commitments (decrease)	0	1
Balance at end of period	113	104
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Provision for Loss, Gross	(2)	(1)
Allowance for Loan and Lease Losses, Write-offs	3	6
Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	54	44
Allowance for Loan and Lease Losses, Adjustments, Other	0	5
Balance at end of period	0	0
Allowance for loan losses	54	44	56	54	40	44
Reserve for unfunded lending commitments	0	0	0	$ 0	0	$ 0
Allowance for loan and lease losses and reserve for unfunded lending commitments			$ 56		$ 40
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	3	1
Provision for Unfunded Lending Commitments (decrease)	0	0
Balance at end of period	$ 56	$ 40