Annual report pursuant to Section 13 and 15(d)

Derivatives - Derivatives Designated as Fair Value Hedges (Details)

v3.8.0.1
Derivatives - Derivatives Designated as Fair Value Hedges (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Effect of Fair Value Hedges on Results of Operations [Abstract]      
Derivative $ 207 $ (2,202) $ (2,511)
Hedged Item (687) 1,304 1,608
Hedge Ineffectiveness (480) (898) (903)
Interest rate risk on long-term debt | Interest expense      
Effect of Fair Value Hedges on Results of Operations [Abstract]      
Derivative (1,537) (1,488) (718)
Hedged Item 1,045 646 (77)
Hedge Ineffectiveness (492) (842) (795)
Interest rate and foreign currency risk on long-term debt | Interest expense      
Effect of Fair Value Hedges on Results of Operations [Abstract]      
Derivative 1,811 (941) (1,898)
Hedged Item (1,767) 944 1,812
Hedge Ineffectiveness 44 3 (86)
Interest rate risk on AFS securities | Interest income      
Effect of Fair Value Hedges on Results of Operations [Abstract]      
Derivative (67) 227 105
Hedged Item 35 (286) (127)
Hedge Ineffectiveness $ (32) $ (59) $ (22)