Quarterly report pursuant to Section 13 or 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
Sep. 30, 2017
Dec. 31, 2016
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [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 $ 35  
Due after One Year through Five Years, Yield 3.66%  
Due after Five Years through Ten Years, Amount $ 1,074  
Due after Five Years though Ten Years, Yield 2.56%  
Due after Ten Years, Amount $ 121,236  
Due after Ten Years, Yield 3.03%  
Amortized Cost $ 122,345 $ 117,071
Total, Yield 3.03%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Debt securities carried at fair value $ 316,864 313,660
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]    
Due in One Year or Less, Amount 0  
Due after One Year through Five Years, Amount 27  
Due after Five Years though Ten Years, Amount 896  
Due after Ten Years, Amount 120,262  
Held-to-maturity Securities, Fair Value 121,185 $ 115,285
Agency    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 6  
Due in One Year or Less, Yield 4.67%  
Due after One Year through Five Years, Amount $ 25  
Due after One Year through Five Years, Yield 3.38%  
Due after Five Years though Ten Years, Amount $ 593  
Due after Five Years though Ten Years, Yield 2.56%  
Due after Ten Years, Amount $ 195,906  
Due after Ten Years, Yield 3.23%  
Total, Amount $ 196,530  
Total, Yield 3.23%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 6  
Due after One Year through Five Years, Amount 25  
Due after Five Years though Ten Years, Amount 598  
Due after Ten Years, Amount 195,565  
Debt securities carried at fair value 196,194  
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 $ 34  
Due after Five Years though Ten Years, Yield 2.50%  
Due after Ten Years, Amount $ 6,991  
Due after Ten Years, Yield 3.18%  
Total, Amount $ 7,025  
Total, Yield 3.18%  
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 33  
Due after Ten Years, Amount 7,021  
Debt securities carried at fair value 7,054  
Commercial    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 48  
Due in One Year or Less, Yield 8.11%  
Due after One Year through Five Years, Amount $ 847  
Due after One Year through Five Years, Yield 2.06%  
Due after Five Years though Ten Years, Amount $ 11,183  
Due after Five Years though Ten Years, Yield 2.44%  
Due after Ten Years, Amount $ 506  
Due after Ten Years, Yield 2.70%  
Total, Amount $ 12,584  
Total, Yield 2.45%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 48  
Due after One Year through Five Years, Amount 848  
Due after Five Years though Ten Years, Amount 11,072  
Due after Ten Years, Amount 496  
Debt securities carried at fair value 12,464  
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 $ 26  
Due after Five Years though Ten Years, Yield 0.01%  
Due after Ten Years, Amount $ 5,106  
Due after Ten Years, Yield 9.05%  
Total, Amount $ 5,132  
Total, Yield 9.00%  
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 35  
Due after Ten Years, Amount 5,680  
Debt securities carried at fair value 5,715  
Mortgage-backed securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 54  
Due in One Year or Less, Yield 7.73%  
Due after One Year through Five Years, Amount $ 872  
Due after One Year through Five Years, Yield 2.10%  
Due after Five Years though Ten Years, Amount $ 11,836  
Due after Five Years though Ten Years, Yield 2.44%  
Due after Ten Years, Amount $ 208,509  
Due after Ten Years, Yield 3.37%  
Total, Amount $ 221,271  
Total, Yield 3.32%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 54  
Due after One Year through Five Years, Amount 873  
Due after Five Years though Ten Years, Amount 11,738  
Due after Ten Years, Amount 208,762  
Debt securities carried at fair value 221,427  
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 $ 516  
Due in One Year or Less, Yield 0.39%  
Due after One Year through Five Years, Amount $ 21,254  
Due after One Year through Five Years, Yield 1.40%  
Due after Five Years though Ten Years, Amount $ 29,033  
Due after Five Years though Ten Years, Yield 1.96%  
Due after Ten Years, Amount $ 21  
Due after Ten Years, Yield 2.42%  
Total, Amount $ 50,824  
Total, Yield 1.71%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 516  
Due after One Year through Five Years, Amount 20,992  
Due after Five Years though Ten Years, Amount 28,739  
Due after Ten Years, Amount 21  
Debt securities carried at fair value 50,268  
Non-U.S. securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 16,563  
Due in One Year or Less, Yield 0.50%  
Due after One Year through Five Years, Amount $ 1,839  
Due after One Year through Five Years, Yield 1.24%  
Due after Five Years though Ten Years, Amount $ 110  
Due after Five Years though Ten Years, Yield 1.34%  
Due after Ten Years, Amount $ 177  
Due after Ten Years, Yield 6.52%  
Total, Amount $ 18,689  
Total, Yield 0.63%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 16,563  
Due after One Year through Five Years, Amount 1,844  
Due after Five Years though Ten Years, Amount 111  
Due after Ten Years, Amount 182  
Debt securities carried at fair value 18,700  
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 $ 1,747  
Due in One Year or Less, Yield 2.28%  
Due after One Year through Five Years, Amount $ 2,865  
Due after One Year through Five Years, Yield 2.59%  
Due after Five Years though Ten Years, Amount $ 1,418  
Due after Five Years though Ten Years, Yield 2.95%  
Due after Ten Years, Amount $ 1,151  
Due after Ten Years, Yield 3.28%  
Total, Amount $ 7,181  
Total, Yield 2.70%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 1,747  
Due after One Year through Five Years, Amount 2,845  
Due after Five Years though Ten Years, Amount 1,450  
Due after Ten Years, Amount 1,235  
Debt securities carried at fair value 7,277  
Total taxable securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 18,880  
Due in One Year or Less, Yield 0.68%  
Due after One Year through Five Years, Amount $ 26,830  
Due after One Year through Five Years, Yield 1.54%  
Due after Five Years though Ten Years, Amount $ 42,397  
Due after Five Years though Ten Years, Yield 2.13%  
Due after Ten Years, Amount $ 209,858  
Due after Ten Years, Yield 3.37%  
Total, Amount $ 297,965  
Total, Yield 2.86%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 18,880  
Due after One Year through Five Years, Amount 26,554  
Due after Five Years though Ten Years, Amount 42,038  
Due after Ten Years, Amount 210,200  
Debt securities carried at fair value 297,672  
Tax-exempt securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 1,175  
Due in One Year or Less, Yield 1.46%  
Due after One Year through Five Years, Amount $ 6,428  
Due after One Year through Five Years, Yield 1.77%  
Due after Five Years though Ten Years, Amount $ 9,155  
Due after Five Years though Ten Years, Yield 1.66%  
Due after Ten Years, Amount $ 2,359  
Due after Ten Years, Yield 2.03%  
Total, Amount $ 19,117  
Total, Yield 1.73%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 1,174  
Due after One Year through Five Years, Amount 6,451  
Due after Five Years though Ten Years, Amount 9,202  
Due after Ten Years, Amount 2,365  
Debt securities carried at fair value 19,192  
Debt securities    
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 20,055  
Due in One Year or Less, Yield 0.73%  
Due after One Year through Five Years, Amount $ 33,258  
Due after One Year through Five Years, Yield 1.58%  
Due after Five Years though Ten Years, Amount $ 51,552  
Due after Five Years though Ten Years, Yield 2.04%  
Due after Ten Years, Amount $ 212,217  
Due after Ten Years, Yield 3.36%  
Total, Amount $ 317,082  
Total, Yield 2.79%  
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]    
Due in One Year or Less, Amount $ 20,054  
Due after One Year through Five Years, Amount 33,005  
Due after Five Years though Ten Years, Amount 51,240  
Due after Ten Years, Amount 212,565  
Debt securities carried at fair value $ 316,864