Annual report pursuant to Section 13 and 15(d)

Securities - Maturities of Debt Securities Carried at Fair Value and Held-to-maturity Debt Securities (Details)

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Securities - Maturities of Debt Securities Carried at Fair Value and Held-to-maturity Debt Securities (Details) - USD ($)
$ in Millions
Dec. 31, 2018
Dec. 31, 2017
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]    
Due in One Year or Less, Amount $ 657  
Due in One Year or Less, Yield 5.78%  
Due after One Year through Five Years, Amount $ 18  
Due after One Year through Five Years, Yield 3.93%  
Due after Five Years through Ten Years, Amount $ 1,475  
Due after Five Years though Ten Years, Yield 2.89%  
Due after Ten Years, Amount $ 201,502  
Due after Ten Years, Yield 3.23%  
Amortized Cost $ 203,652 $ 125,013
Total, Yield 3.24%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Debt securities carried at fair value $ 238,101 315,117
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]    
Due in One Year or Less, Amount 657  
Due after One Year through Five Years, Amount 18  
Due after Five Years though Ten Years, Amount 1,429  
Due after Ten Years, Amount 198,331  
Debt Securities, Held-to-maturity, Fair Value 200,435 $ 123,299
Mortgage-backed securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 198  
Due in One Year or Less, Yield 1.78%  
Due after One Year through Five Years, Amount $ 2,581  
Due after One Year through Five Years, Yield 2.36%  
Due after Five Years though Ten Years, Amount $ 12,265  
Due after Five Years though Ten Years, Yield 2.51%  
Due after Ten Years, Amount $ 133,444  
Due after Ten Years, Yield 3.49%  
Total, Amount $ 148,488  
Total, Yield 3.39%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 198  
Due after One Year through Five Years, Amount 2,539  
Due after Five Years though Ten Years, Amount 11,928  
Due after Ten Years, Amount 130,292  
Debt securities carried at fair value 144,957  
Agency    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due in One Year or Less, Yield 0.00%  
Due after One Year through Five Years, Amount $ 114  
Due after One Year through Five Years, Yield 2.42%  
Due after Five Years though Ten Years, Amount $ 1,245  
Due after Five Years though Ten Years, Yield 2.39%  
Due after Ten Years, Amount $ 123,757  
Due after Ten Years, Yield 3.34%  
Total, Amount $ 125,116  
Total, Yield 3.33%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due after One Year through Five Years, Amount 114  
Due after Five Years though Ten Years, Amount 1,219  
Due after Ten Years, Amount 120,493  
Debt securities carried at fair value 121,826  
Agency-collateralized mortgage obligations    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due in One Year or Less, Yield 0.00%  
Due after One Year through Five Years, Amount $ 0  
Due after One Year through Five Years, Yield 0.00%  
Due after Five Years though Ten Years, Amount $ 30  
Due after Five Years though Ten Years, Yield 2.50%  
Due after Ten Years, Amount $ 5,591  
Due after Ten Years, Yield 3.17%  
Total, Amount $ 5,621  
Total, Yield 3.17%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due after One Year through Five Years, Amount 0  
Due after Five Years though Ten Years, Amount 29  
Due after Ten Years, Amount 5,501  
Debt securities carried at fair value 5,530  
Commercial    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 198  
Due in One Year or Less, Yield 1.78%  
Due after One Year through Five Years, Amount $ 2,467  
Due after One Year through Five Years, Yield 2.36%  
Due after Five Years though Ten Years, Amount $ 10,976  
Due after Five Years though Ten Years, Yield 2.53%  
Due after Ten Years, Amount $ 828  
Due after Ten Years, Yield 2.96%  
Total, Amount $ 14,469  
Total, Yield 2.52%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 198  
Due after One Year through Five Years, Amount 2,425  
Due after Five Years though Ten Years, Amount 10,656  
Due after Ten Years, Amount 799  
Debt securities carried at fair value 14,078  
Non-agency residential    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due in One Year or Less, Yield 0.00%  
Due after One Year through Five Years, Amount $ 0  
Due after One Year through Five Years, Yield 0.00%  
Due after Five Years though Ten Years, Amount $ 14  
Due after Five Years though Ten Years, Yield 0.00%  
Due after Ten Years, Amount $ 3,268  
Due after Ten Years, Yield 9.88%  
Total, Amount $ 3,282  
Total, Yield 9.84%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 0  
Due after One Year through Five Years, Amount 0  
Due after Five Years though Ten Years, Amount 24  
Due after Ten Years, Amount 3,499  
Debt securities carried at fair value 3,523  
U.S. Treasury and agency securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 670  
Due in One Year or Less, Yield 0.78%  
Due after One Year through Five Years, Amount $ 33,659  
Due after One Year through Five Years, Yield 1.48%  
Due after Five Years though Ten Years, Amount $ 23,159  
Due after Five Years though Ten Years, Yield 2.36%  
Due after Ten Years, Amount $ 21  
Due after Ten Years, Yield 2.57%  
Total, Amount $ 57,509  
Total, Yield 1.83%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 669  
Due after One Year through Five Years, Amount 32,694  
Due after Five Years though Ten Years, Amount 22,821  
Due after Ten Years, Amount 21  
Debt securities carried at fair value 56,205  
Non-U.S. securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 14,318  
Due in One Year or Less, Yield 1.30%  
Due after One Year through Five Years, Amount $ 682  
Due after One Year through Five Years, Yield 1.88%  
Due after Five Years though Ten Years, Amount $ 21  
Due after Five Years though Ten Years, Yield 4.43%  
Due after Ten Years, Amount $ 121  
Due after Ten Years, Yield 6.57%  
Total, Amount $ 15,142  
Total, Yield 1.37%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 14,315  
Due after One Year through Five Years, Amount 692  
Due after Five Years though Ten Years, Amount 19  
Due after Ten Years, Amount 124  
Debt securities carried at fair value 15,150  
Other taxable securities, substantially all asset-backed securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 1,591  
Due in One Year or Less, Yield 3.34%  
Due after One Year through Five Years, Amount $ 2,022  
Due after One Year through Five Years, Yield 3.54%  
Due after Five Years though Ten Years, Amount $ 688  
Due after Five Years though Ten Years, Yield 3.48%  
Due after Ten Years, Amount $ 86  
Due after Ten Years, Yield 5.59%  
Total, Amount $ 4,387  
Total, Yield 3.49%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 1,585  
Due after One Year through Five Years, Amount 2,043  
Due after Five Years though Ten Years, Amount 698  
Due after Ten Years, Amount 87  
Debt securities carried at fair value 4,413  
Total taxable securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 16,777  
Due in One Year or Less, Yield 1.48%  
Due after One Year through Five Years, Amount $ 38,944  
Due after One Year through Five Years, Yield 1.66%  
Due after Five Years though Ten Years, Amount $ 36,133  
Due after Five Years though Ten Years, Yield 2.43%  
Due after Ten Years, Amount $ 133,672  
Due after Ten Years, Yield 3.49%  
Total, Amount $ 225,526  
Total, Yield 2.85%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 16,767  
Due after One Year through Five Years, Amount 37,968  
Due after Five Years though Ten Years, Amount 35,466  
Due after Ten Years, Amount 130,524  
Debt securities carried at fair value 220,725  
Tax-exempt securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 938  
Due in One Year or Less, Yield 2.59%  
Due after One Year through Five Years, Amount $ 7,526  
Due after One Year through Five Years, Yield 2.59%  
Due after Five Years though Ten Years, Amount $ 6,162  
Due after Five Years though Ten Years, Yield 2.44%  
Due after Ten Years, Amount $ 2,723  
Due after Ten Years, Yield 2.55%  
Total, Amount $ 17,349  
Total, Yield 2.53%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 936  
Due after One Year through Five Years, Amount 7,537  
Due after Five Years though Ten Years, Amount 6,184  
Due after Ten Years, Amount 2,719  
Debt securities carried at fair value 17,376  
Debt securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 17,715  
Due in One Year or Less, Yield 1.54%  
Due after One Year through Five Years, Amount $ 46,470  
Due after One Year through Five Years, Yield 1.81%  
Due after Five Years though Ten Years, Amount $ 42,295  
Due after Five Years though Ten Years, Yield 2.43%  
Due after Ten Years, Amount $ 136,395  
Due after Ten Years, Yield 3.47%  
Total, Amount $ 242,875  
Total, Yield 2.83%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 17,703  
Due after One Year through Five Years, Amount 45,505  
Due after Five Years though Ten Years, Amount 41,650  
Due after Ten Years, Amount 133,243  
Debt securities carried at fair value $ 238,101