Annual report pursuant to Section 13 and 15(d)

Securities - Temporarily Impaired and Other-than-temporarily Impaired AFS Debt Securities (Details)

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Securities - Temporarily Impaired and Other-than-temporarily Impaired AFS Debt Securities (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Credit-related OTTI losses $ 41 $ 19 $ 81
Other than temporary impairment losses recorded on debt securities 0 0 0
Cumulative credit losses on debt securities held 274 253 $ 266
Debt securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 111,645 181,821  
Less than Twelve Months, Gross Unrealized Losses (693) (3,072)  
Twelve Months or Longer, Fair Value 110,109 8,856  
Twelve Months or Longer, Gross Unrealized Losses (2,425) (228)  
Total, Fair Value 221,754 190,677  
Total, Gross Unrealized Losses (3,118) (3,300)  
Temporarily impaired AFS debt securities | Debt securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 111,587 181,727  
Less than Twelve Months, Gross Unrealized Losses (692) (3,071)  
Twelve Months or Longer, Fair Value 110,109 8,455  
Twelve Months or Longer, Gross Unrealized Losses (2,425) (212)  
Total, Fair Value 221,696 190,182  
Total, Gross Unrealized Losses (3,117) (3,283)  
Temporarily impaired AFS debt securities | Mortgage-backed securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 82,188 147,669  
Less than Twelve Months, Gross Unrealized Losses (438) (2,165)  
Twelve Months or Longer, Fair Value 78,882 5,002  
Twelve Months or Longer, Gross Unrealized Losses (1,554) (156)  
Total, Fair Value 161,070 152,671  
Total, Gross Unrealized Losses (1,992) (2,321)  
Temporarily impaired AFS debt securities | Agency      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 73,535 135,210  
Less than Twelve Months, Gross Unrealized Losses (352) (1,846)  
Twelve Months or Longer, Fair Value 72,612 3,770  
Twelve Months or Longer, Gross Unrealized Losses (1,344) (117)  
Total, Fair Value 146,147 138,980  
Total, Gross Unrealized Losses (1,696) (1,963)  
Temporarily impaired AFS debt securities | Agency-collateralized mortgage obligations      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 2,743 3,229  
Less than Twelve Months, Gross Unrealized Losses (29) (25)  
Twelve Months or Longer, Fair Value 1,684 1,028  
Twelve Months or Longer, Gross Unrealized Losses (52) (26)  
Total, Fair Value 4,427 4,257  
Total, Gross Unrealized Losses (81) (51)  
Temporarily impaired AFS debt securities | Commercial      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 5,575 9,018  
Less than Twelve Months, Gross Unrealized Losses (50) (293)  
Twelve Months or Longer, Fair Value 4,586 0  
Twelve Months or Longer, Gross Unrealized Losses (158) 0  
Total, Fair Value 10,161 9,018  
Total, Gross Unrealized Losses (208) (293)  
Temporarily impaired AFS debt securities | Non-agency residential      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 335 212  
Less than Twelve Months, Gross Unrealized Losses (7) (1)  
Twelve Months or Longer, Fair Value 0 204  
Twelve Months or Longer, Gross Unrealized Losses 0 (13)  
Total, Fair Value 335 416  
Total, Gross Unrealized Losses (7) (14)  
Temporarily impaired AFS debt securities | U.S. Treasury and agency securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 27,537 28,462  
Less than Twelve Months, Gross Unrealized Losses (251) (752)  
Twelve Months or Longer, Fair Value 24,035 0  
Twelve Months or Longer, Gross Unrealized Losses (767) 0  
Total, Fair Value 51,572 28,462  
Total, Gross Unrealized Losses (1,018) (752)  
Temporarily impaired AFS debt securities | Non-U.S. securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 772 52  
Less than Twelve Months, Gross Unrealized Losses (1) (1)  
Twelve Months or Longer, Fair Value 0 142  
Twelve Months or Longer, Gross Unrealized Losses 0 (2)  
Total, Fair Value 772 194  
Total, Gross Unrealized Losses (1) (3)  
Temporarily impaired AFS debt securities | Other taxable securities, substantially all asset-backed securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 0 762  
Less than Twelve Months, Gross Unrealized Losses 0 (5)  
Twelve Months or Longer, Fair Value 92 1,438  
Twelve Months or Longer, Gross Unrealized Losses (2) (18)  
Total, Fair Value 92 2,200  
Total, Gross Unrealized Losses (2) (23)  
Temporarily impaired AFS debt securities | Total taxable securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 110,497 176,945  
Less than Twelve Months, Gross Unrealized Losses (690) (2,923)  
Twelve Months or Longer, Fair Value 103,009 6,582  
Twelve Months or Longer, Gross Unrealized Losses (2,323) (176)  
Total, Fair Value 213,506 183,527  
Total, Gross Unrealized Losses (3,013) (3,099)  
Temporarily impaired AFS debt securities | Tax-exempt securities      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 1,090 4,782  
Less than Twelve Months, Gross Unrealized Losses (2) (148)  
Twelve Months or Longer, Fair Value 7,100 1,873  
Twelve Months or Longer, Gross Unrealized Losses (102) (36)  
Total, Fair Value 8,190 6,655  
Total, Gross Unrealized Losses (104) (184)  
Other-than-temporarily impaired AFS debt securities | Non-agency residential      
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]      
Less than Twelve Months, Fair Value 58 94  
Less than Twelve Months, Gross Unrealized Losses (1) (1)  
Twelve Months or Longer, Fair Value 0 401  
Twelve Months or Longer, Gross Unrealized Losses 0 (16)  
Total, Fair Value 58 495  
Total, Gross Unrealized Losses $ (1) $ (17)