Asset Quality (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions	Mar. 31, 2019		Dec. 31, 2018		Mar. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 232,293	[1]	$ 226,245	[1]	$ 221,614
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	158,442		152,282		$ 148,945
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	122,993		116,834
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,101		28,140
Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,348		7,308
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	151,823		146,138
Pass [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	117,366		111,276
Pass [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,251		27,682
Pass [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,206		7,180
Criticized [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,619		6,144
Criticized [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,627		5,558
Criticized [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	850		458
Criticized [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 142		$ 128

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $.6 billion, Loans of $.8 billion and Other assets of $.1 billion at March 31, 2019 and Loans held for sale of $.9 billion, Loans of $.8 billion and Other assets of $.2 billion at December 31, 2018.