Asset Quality (Consumer Real Estate Secured Asset Quality Indicators) (Details) - USD ($) $ in Millions	Sep. 30, 2019		Dec. 31, 2018		Sep. 30, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 237,377	[1]	$ 226,245	[1]	$ 223,053
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	24,971		26,123
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,082		18,657
FICO Score- Greater than 660 [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,066		22,996
FICO Score- Greater than 660 [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	18,455		15,956
FICO Score- Less than or equal to 660 [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,045		2,210
FICO Score- Less than or equal to 660 [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	547		585
No FICO Score Available [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	282		238
No FICO Score Available [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	291		93
Purchased Impaired Loans [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	578		679
Purchased Impaired Loans [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,216		1,338
Loans Insured or Guaranteed by US Government Authorities [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	573		685
LTV Greater Than Or Equal To 125 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	382		461
LTV Greater Than Or Equal To 125 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	123		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	911		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	228		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	1,096		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	340		335
LTV Less Than 90 Percent [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,821		22,644
LTV Less Than 90 Percent [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	18,384		15,922
No LTV Ratio Available [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	183		145
No LTV Ratio Available [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 218		$ 6

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.5 billion, Loans of $.8 billion and Other assets of $.1 billion at September 30, 2019 and Loans held for sale of $.9 billion, Loans of $.8 billion and Other assets of $.2 billion at December 31, 2018.