Asset Quality (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 226,245	[1]	$ 220,458	[1]	$ 210,833
Total commercial lending
Financing Receivable, Recorded Investment [Line Items]
Total Loans	152,282		147,439		$ 137,955
Total commercial lending | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	116,834		110,527
Total commercial lending | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	28,140		28,978
Total commercial lending | Equipment Lease Financing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,308		7,934
Pass | Total commercial lending
Financing Receivable, Recorded Investment [Line Items]
Total Loans	146,138		141,414
Pass | Total commercial lending | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	111,276		105,280
Pass | Total commercial lending | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,682		28,380
Pass | Total commercial lending | Equipment Lease Financing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	7,180		7,754
Criticized | Total commercial lending
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,144		6,025
Criticized | Total commercial lending | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,558		5,247
Criticized | Total commercial lending | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	458		598
Criticized | Total commercial lending | Equipment Lease Financing
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 128		$ 180

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $.9 billion, Loans of $.8 billion, and Other assets of $.2 billion at December 31, 2018 and Loans held for sale of $1.7 billion, Loans of $.9 billion, and Other assets of $.3 billion at December 31, 2017.