Quarterly report pursuant to Section 13 or 15(d)

Securitizations and Other Variable Interest Entities - Other Asset-backed Securitizations Additional Information (Details)

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Securitizations and Other Variable Interest Entities - Other Asset-backed Securitizations Additional Information (Details) - USD ($)
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Variable Interest Entity [Line Items]          
Home equity lines of credit funded     $ 1,000,000 $ 6,000,000  
Home equity          
Variable Interest Entity [Line Items]          
Trust certificates outstanding $ 3,300,000,000   3,300,000,000   $ 4,000,000,000
Credit Card Receivable          
Variable Interest Entity [Line Items]          
Principal amount outstanding $ 7,500,000,000   $ 7,500,000,000   $ 7,500,000,000
Transferred financial assets, stated interest rate 0.00%   0.00%   0.00%
Credit Card Receivable | Senior Lien          
Variable Interest Entity [Line Items]          
Transferred financial assets, amount issued $ 0 $ 0 $ 750,000,000 2,300,000,000  
Credit Card Receivable | Junior Lien          
Variable Interest Entity [Line Items]          
Transferred financial assets, amount issued 0 0 121,000,000 371,000,000  
Resecuritization Trusts          
Variable Interest Entity [Line Items]          
Cash proceeds from new securitizations 5,600,000,000 9,100,000,000 20,300,000,000 22,100,000,000  
Resecuritization Trusts | Available-for-sale Securities          
Variable Interest Entity [Line Items]          
Cash proceeds from new securitizations 0 0 0 0  
Resecuritization Trusts | Debt securities          
Variable Interest Entity [Line Items]          
Cash proceeds from new securitizations 430,000,000 3,500,000,000 2,600,000,000 5,200,000,000  
Resecuritization Trusts | Other Security Investments          
Variable Interest Entity [Line Items]          
Gain on sale of investments 0 $ 0 0 $ 0  
Municipal Bond Trusts | Unconsolidated VIEs          
Variable Interest Entity [Line Items]          
Liquidity commitments to unconsolidated securitization trusts 1,700,000,000   $ 1,700,000,000   $ 1,600,000,000
Weighted average remaining life of bonds held in the trusts in years     6 years 2 months 12 days    
Automobile and Other Securitization Trusts          
Variable Interest Entity [Line Items]          
Principal amount outstanding 179,000,000   $ 179,000,000   314,000,000
Other Loan and Receivable          
Variable Interest Entity [Line Items]          
Principal amount outstanding 179,000,000   179,000,000   189,000,000
Automobile Loan          
Variable Interest Entity [Line Items]          
Principal amount outstanding $ 0   $ 0   $ 125,000,000