Derivative Instruments - Impact on Statements of Income, Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Gains/(losses) recorded in income
Derivatives	$ 2,034	$ (13)	$ 2,920	$ (1,162)
Hedged items	(1,682)	281	(2,272)	1,730
Income statement impact	352	268	648	568
Income statement impact of excluded components:
Amortization approach	(229)	(145)	(451)	(267)
Changes in fair value	338	290	630	566
OCI impact
Derivatives - Gains/(losses) recorded in OCI	112	(89)	115	(141)
Interest rate
Gains/(losses) recorded in income
Derivatives	1,762	(400)	3,226	(1,877)
Hedged items	(1,556)	553	(2,849)	2,182
Income statement impact	206	153	377	305
Income statement impact of excluded components:
Amortization approach	0	0	0	0
Changes in fair value	196	152	368	299
OCI impact
Derivatives - Gains/(losses) recorded in OCI	0	0	0	0
Foreign exchange
Gains/(losses) recorded in income
Derivatives	426	376	136	520
Hedged items	(301)	(254)	108	(287)
Income statement impact	125	122	244	233
Income statement impact of excluded components:
Amortization approach	(229)	(145)	(451)	(267)
Changes in fair value	125	122	244	233
OCI impact
Derivatives - Gains/(losses) recorded in OCI	112	(89)	115	(141)
Commodity
Gains/(losses) recorded in income
Derivatives	(154)	11	(442)	195
Hedged items	175	(18)	469	(165)
Income statement impact	21	(7)	27	30
Income statement impact of excluded components:
Amortization approach	0	0	0	0
Changes in fair value	17	16	18	34
OCI impact
Derivatives - Gains/(losses) recorded in OCI	$ 0	$ 0	$ 0	$ 0