Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 209	$ 146
Nonaccrual loans		631	367
Current loans		48,434	48,571
Total loans		49,274	49,084
30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		132	108
60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		29	21
90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		48	17
Business loans | Commercial borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		165	104
Nonaccrual loans		577	313
Current loans		44,117	44,312
Total loans		44,859	44,729
Business loans | Commercial borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		112	70
Business loans | Commercial borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		26	17
Business loans | Commercial borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		27	17
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		106	71
Nonaccrual loans		508	238
Current loans		30,538	31,350
Total loans		31,152	31,659
Business loans | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		68	46
Business loans | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		17	12
Business loans | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		21	13
Business loans | Commercial borrower | International loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	2
Nonaccrual loans		19	8
Current loans		1,283	1,358
Total loans		1,303	1,368
Business loans | Commercial borrower | International loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	2
Business loans | Commercial borrower | International loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Commercial borrower | International loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		23	8
Nonaccrual loans		0	1
Current loans		2,720	1,992
Total loans		2,743	2,001
Business loans | Real estate construction | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		23	8
Business loans | Real estate construction | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	12	5
Nonaccrual loans	[1]	0	0
Current loans	[1]	2,370	1,676
Total loans	[1],[2]	2,382	1,681
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	12	5
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	11	3
Nonaccrual loans	[3]	0	1
Current loans	[3]	350	316
Total loans	[3],[4]	361	320
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	11	3
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		35	23
Nonaccrual loans		44	60
Current loans		8,934	8,894
Total loans		9,013	8,977
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		20	14
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		9	5
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	4
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	6	8
Nonaccrual loans	[1]	8	16
Current loans	[1]	2,171	2,080
Total loans	[1],[2]	2,185	2,104
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	5	7
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	1	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	1
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	29	15
Nonaccrual loans	[3]	36	44
Current loans	[3]	6,763	6,814
Total loans	[3],[4]	6,828	6,873
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	15	7
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	8	5
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[3]	6	3
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Nonaccrual loans		6	6
Current loans		642	718
Total loans		648	724
Business loans | Lease financing | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		44	42
Nonaccrual loans		54	54
Current loans		4,317	4,259
Total loans		4,415	4,355
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		20	38
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		3	4
Retail loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		21	0
Retail loans | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		21	15
Nonaccrual loans		31	27
Current loans		2,489	2,443
Total loans		2,541	2,485
Retail loans | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		7	12
Retail loans | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	3
Retail loans | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		12	0
Retail loans | Real estate mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		23	27
Nonaccrual loans		23	27
Current loans		1,828	1,816
Total loans		1,874	1,870
Retail loans | Real estate mortgage | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		13	26
Retail loans | Real estate mortgage | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	1
Retail loans | Real estate mortgage | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		9	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		8	8
Nonaccrual loans		27	27
Current loans		1,757	1,685
Total loans		1,792	1,720
Retail loans | Home equity | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	5
Retail loans | Home equity | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	3
Retail loans | Home equity | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		13	7
Nonaccrual loans		4	0
Current loans		732	758
Total loans		749	765
Retail loans | Other consumer | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		1	7
Retail loans | Other consumer | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 12	$ 0

[1] Primarily loans to real estate developers.

[2] Primarily loans to real estate developers.

[3] Primarily loans secured by owner-occupied real estate.

[4] Primarily loans secured by owner-occupied real estate.