Asset Quality (Commercial Lending 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
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	160,188		152,282		$ 149,448
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	124,014		116,834
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,884		28,140
Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,290		7,308
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	153,431		146,138
Pass [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	118,316		111,276
Pass [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,050		27,682
Pass [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,065		7,180
Criticized [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,757		6,144
Criticized [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,698		5,558
Criticized [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	834		458
Criticized [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 225		$ 128

[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.