Asset Quality (Consumer Real Estate Secured Asset Quality Indicators) (Details) - USD ($) $ in Millions	Jun. 30, 2019		Dec. 31, 2018		Jun. 30, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 237,215	[1]	$ 226,245	[1]	$ 222,855
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	25,132		26,123
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	20,092		18,657
FICO Score- Greater than 660 [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,186		22,996
FICO Score- Greater than 660 [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	17,450		15,956
FICO Score- Less than or equal to 660 [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,067		2,210
FICO Score- Less than or equal to 660 [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	568		585
No FICO Score Available [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	265		238
No FICO Score Available [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	224		93
Purchased Impaired Loans [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	614		679
Purchased Impaired Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,257		1,338
Loans Insured or Guaranteed by US Government Authorities [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	593		685
LTV Greater Than Or Equal To 125 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	432		461
LTV Greater Than Or Equal To 125 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	129		116
LTV Greater Than Or Equal To 100 Percent To Less Than 125 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	991		1,020
LTV Greater Than Or Equal To 100 Percent To Less Than 125 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	248		255
LTV Greater Than Or Equal To 90 Percent To Less Than 100 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,200		1,174
LTV Greater Than Or Equal To 90 Percent To Less Than 100 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	358		335
LTV Less Than 90 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,732		22,644
LTV Less Than 90 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	17,359		15,922
No LTV Ratio Available [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	163		145
No LTV Ratio Available [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 148		$ 6

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.1 billion, Loans of $.8 billion and Other assets of $.1 billion at June 30, 2019 and Loans held for sale of $.9 billion, Loans of $.8 billion and Other assets of $.2 billion at December 31, 2018.