Quarterly report pursuant to Section 13 or 15(d)

Allowance for Credit Losses - Allowance by Portfolio Segment (Details)

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Allowance for Credit Losses - Allowance by Portfolio Segment (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2017
Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]        
Allowance for loan and lease losses, beginning of the period $ 10,393 $ 11,237    
Loans and leases charged off (1,296) (1,310)    
Recoveries of loans and leases previously charged off 385 376    
Net charge-offs (911) (934)    
Provision for loan and lease losses 829 840    
Other (16) 2    
Allowance for loan and lease losses, end of the period 10,260 11,112    
Provision for unfunded lending commitments 834 835    
Reserve for unfunded lending commitments, end of the period 11,042 11,869    
Allowance for credit losses 11,042 11,869 $ 11,869  
Unfunded loan commitments        
Allowance for Loan and Lease Losses [Roll Forward]        
Reserve for unfunded lending commitments, beginning of the period 777 762    
Provision for unfunded lending commitments 5 (5)    
Reserve for unfunded lending commitments, end of the period 782 757    
Allowance for credit losses 777 762 757 $ 762
Purchased Credit-impaired        
Allowance for Loan and Lease Losses [Roll Forward]        
Loans and leases charged off (35) (33)    
Provision for loan and lease losses (11) 68    
Reserve for unfunded lending commitments, beginning of the period 289      
Reserve for unfunded lending commitments, end of the period 242      
Allowance for credit losses 289      
Financing receivable allowance sold 16 0    
Consumer Real Estate        
Allowance for Loan and Lease Losses [Roll Forward]        
Allowance for loan and lease losses, beginning of the period 1,720 2,750    
Loans and leases charged off (174) (204)    
Recoveries of loans and leases previously charged off 147 123    
Net charge-offs (27) (81)    
Provision for loan and lease losses (128) (71)    
Other 0 0    
Allowance for loan and lease losses, end of the period 1,530 2,565    
Reserve for unfunded lending commitments, end of the period 1,530 2,565    
Allowance for credit losses 1,530 2,565 2,565  
Consumer Real Estate | Unfunded loan commitments        
Allowance for Loan and Lease Losses [Roll Forward]        
Reserve for unfunded lending commitments, beginning of the period 0 0    
Provision for unfunded lending commitments 0 0    
Reserve for unfunded lending commitments, end of the period 0 0    
Allowance for credit losses 0 0 0 0
Consumer Real Estate | Purchased Credit-impaired        
Allowance for Loan and Lease Losses [Roll Forward]        
Loans and leases charged off (35) (33)    
Reserve for unfunded lending commitments, beginning of the period 289      
Reserve for unfunded lending commitments, end of the period 242      
Allowance for credit losses 289      
Credit card and other consumer        
Allowance for Loan and Lease Losses [Roll Forward]        
Allowance for loan and lease losses, beginning of the period 3,663 3,229    
Loans and leases charged off (1,006) (946)    
Recoveries of loans and leases previously charged off 203 200    
Net charge-offs (803) (746)    
Provision for loan and lease losses 876 843    
Other (16) 3    
Allowance for loan and lease losses, end of the period 3,720 3,329    
Reserve for unfunded lending commitments, end of the period 3,720 3,329    
Allowance for credit losses 3,720 3,329 3,329  
Credit card and other consumer | Non United States        
Allowance for Loan and Lease Losses [Roll Forward]        
Allowance for loan and lease losses related to disposal group     242 243
Credit card and other consumer | Unfunded loan commitments        
Allowance for Loan and Lease Losses [Roll Forward]        
Reserve for unfunded lending commitments, beginning of the period 0 0    
Provision for unfunded lending commitments 0 0    
Reserve for unfunded lending commitments, end of the period 0 0    
Allowance for credit losses 0 0 0 0
Credit card and other consumer | Credit Card Receivable | Non United States        
Allowance for Loan and Lease Losses [Roll Forward]        
Net charge-offs   (44)    
Credit card and other consumer | Purchased Credit-impaired        
Allowance for Loan and Lease Losses [Roll Forward]        
Loans and leases charged off 0 0    
Commercial        
Allowance for Loan and Lease Losses [Roll Forward]        
Allowance for loan and lease losses, beginning of the period 5,010 5,258    
Loans and leases charged off (116) (160)    
Recoveries of loans and leases previously charged off 35 53    
Net charge-offs (81) (107)    
Provision for loan and lease losses 81 68    
Other 0 (1)    
Allowance for loan and lease losses, end of the period 5,010 5,218    
Reserve for unfunded lending commitments, end of the period 5,792 5,975    
Allowance for credit losses 5,792 5,975 5,975  
Commercial | Unfunded loan commitments        
Allowance for Loan and Lease Losses [Roll Forward]        
Reserve for unfunded lending commitments, beginning of the period 777 762    
Provision for unfunded lending commitments 5 (5)    
Reserve for unfunded lending commitments, end of the period 782 757    
Allowance for credit losses 777 762 $ 757 $ 762
Commercial | Purchased Credit-impaired        
Allowance for Loan and Lease Losses [Roll Forward]        
Loans and leases charged off $ 0 $ 0