Asset Quality (Commercial Lending 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
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	161,603		152,282		$ 149,636
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	125,624		116,834
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,570		28,140
Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,409		7,308
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	155,107		146,138
Pass [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	120,157		111,276
Pass [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,699		27,682
Pass [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,251		7,180
Criticized [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,496		6,144
Criticized [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,467		5,558
Criticized [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	871		458
Criticized [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 158		$ 128

[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.