Credit Quality And Allowance For Credit Losses Credit Quality And Allowance For Credit Losses (Troubled Debt Restructuring Subsequent Default) (Details) - Principal Deferrals - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Modifications [Line Items]
Balance		$ 234	$ 145		$ 234	$ 145
Subsequent default during period		0	1		14	4
Business loans | Commercial borrower
Financing Receivable, Modifications [Line Items]
Balance		233	126		233	126
Subsequent default during period		0	1		14	4
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Modifications [Line Items]
Balance		229	108		229	108
Subsequent default during period		0	1		13	3
Business loans | Commercial borrower | International loans
Financing Receivable, Modifications [Line Items]
Balance		0	2		0	2
Subsequent default during period		0	0		0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans
Financing Receivable, Modifications [Line Items]
Balance		4	16		4	16
Subsequent default during period		0	0		1	1
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Modifications [Line Items]
Balance	[1]	0	9		0	9
Subsequent default during period	[1]	0	0		0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Modifications [Line Items]
Balance	[2]	4	7		4	7
Subsequent default during period	[2]	0	0		1	1
Retail loans
Financing Receivable, Modifications [Line Items]
Balance		1	19		1	19
Subsequent default during period		0	0		0	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Modifications [Line Items]
Balance	[3]	1	1		1	1
Subsequent default during period		0	0		0	0
Retail loans | Real estate mortgage
Financing Receivable, Modifications [Line Items]
Balance		0	18	[3]	0	18	[3]
Subsequent default during period		$ 0	$ 0		$ 0	$ 0

[1] Primarily loans to real estate developers.

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

[3] Includes bankruptcy loans for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt.