Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Principles - Principles of Consolidation and Basis of Presentation (Details)

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Summary of Significant Accounting Principles - Principles of Consolidation and Basis of Presentation (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Jun. 01, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Gain on hedging instrument, tax   $ 2,279 $ 2,349 $ 7,096 $ 5,888  
Loans and leases           $ 9,214
Goodwill   $ 0   $ 0   775
Disposal Group, Disposed of by Sale, Not Discontinued Operations | International Consumer Credit Card Business            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Gain on sale of business, net of tax $ 103          
Gain on sale of business 793          
Proceeds from sale 10,900          
Loans and leases 9,800         9,200
Goodwill 775         $ 775
Disposal Group, Disposed of by Sale, Not Discontinued Operations | International Consumer Credit Card Business | Foreign Exchange Contract            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Gain on hedging instrument, tax $ 690