Annual report pursuant to Section 13 and 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
 12 Months Ended
Jun. 01, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Income tax expense (benefit)   $ 10,981 $ 7,199 $ 6,277
Loans and leases     9,214  
Goodwill     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]        
Income tax expense (benefit) $ 690