Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Jan. 01, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 978	$ 677	$ 668	$ 701
Increase in retail loans allowance for credit losses					$ 25
Provision for credit losses	138	44	549	31
Balance at end of period	$ 1,066	$ 688	$ 1,066	$ 688
As a percentage of total loans	1.99%	1.33%	1.99%	1.33%
As a percentage of total loans excluding PPP Loans	2.15%		2.15%
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Reduction in business loans allowance for credit losses					(42)	$ 0
Increase in retail loans allowance for credit losses					25	0
Day-one decrease in the overall allowance for credit losses					$ (17)	$ 0
Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 916	$ 647	$ 637	$ 671
Loan charge-offs	(57)	(44)	(146)	(64)
Recoveries on loans previously charged-off	7	11	12	20
Net loan charge-offs	(50)	(33)	(134)	(44)
Provision for credit losses	141	43	521	30
Balance at end of period	$ 1,007	$ 657	$ 1,007	$ 657
As a percentage of total loans	1.88%	1.27%	1.88%	1.27%
As a percentage of total loans excluding PPP Loans	2.03%		2.03%
Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 62	$ 30	$ 31	$ 30
Provision for credit losses	(3)	1	28	1
Balance at end of period	59	31	59	31
Business loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	913	635	629	653
Provision for credit losses	130	44	538	37
Balance at end of period	$ 993	$ 646	$ 993	$ 646
As a percentage of total loans	2.01%	1.36%	2.01%	1.36%
As a percentage of total loans excluding PPP Loans	2.18%		2.18%
Business loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 861	$ 608	$ 601	$ 627
Loan charge-offs	(56)	(43)	(143)	(62)
Recoveries on loans previously charged-off	6	10	11	18
Net loan charge-offs	(50)	(33)	(132)	(44)
Provision for credit losses	132	43	516	35
Balance at end of period	$ 943	$ 618	$ 943	$ 618
As a percentage of total loans	1.91%	1.30%	1.91%	1.30%
As a percentage of total loans excluding PPP Loans	2.07%		2.07%
Business loans | Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 52	$ 27	$ 28	$ 26
Provision for credit losses	(2)	1	22	2
Balance at end of period	50	28	50	28
Retail loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	65	42	39	48
Provision for credit losses	8	0	11	6
Balance at end of period	$ 73	$ 42	$ 73	$ 42
As a percentage of total loans	1.82%	0.96%	1.82%	0.96%
Retail loans | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 55	$ 39	$ 36	$ 44
Loan charge-offs	(1)	(1)	(3)	(2)
Recoveries on loans previously charged-off	1	1	1	2
Net loan charge-offs	0	0	(2)	0
Provision for credit losses	9	0	5	5
Balance at end of period	$ 64	$ 39	$ 64	$ 39
As a percentage of total loans	1.59%	0.89%	1.59%	0.89%
Retail loans | Unused Commitments to Extend Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance at beginning of period	$ 10	$ 3	$ 3	$ 4
Provision for credit losses	(1)	0	6	(1)
Balance at end of period	$ 9	$ 3	$ 9	$ 3