Derivative Instruments - Impact on Statements of Income, Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Gains/(losses) recorded in income
Derivatives	$ 1,881	$ (139)	$ 4,801	$ (1,301)
Hedged items	(1,489)	406	(3,761)	2,136
Income statement impact	392	267	1,040	835
Income statement impact of excluded components:
Amortization approach	(224)	(137)	(675)	(404)
Changes in fair value	403	267	1,033	833
OCI impact
Derivatives - Gains/(losses) recorded in OCI	(1)	45	114	(96)
Interest rate
Gains/(losses) recorded in income
Derivatives	1,770	(870)	4,996	(2,747)
Hedged items	(1,550)	1,032	(4,399)	3,214
Income statement impact	220	162	597	467
Income statement impact of excluded components:
Amortization approach	0	0	0	0
Changes in fair value	228	160	596	459
OCI impact
Derivatives - Gains/(losses) recorded in OCI	0	0	0	0
Foreign exchange
Gains/(losses) recorded in income
Derivatives	(167)	277	(31)	797
Hedged items	293	(165)	401	(452)
Income statement impact	126	112	370	345
Income statement impact of excluded components:
Amortization approach	(224)	(137)	(675)	(404)
Changes in fair value	126	112	370	345
OCI impact
Derivatives - Gains/(losses) recorded in OCI	(1)	45	114	(96)
Commodity
Gains/(losses) recorded in income
Derivatives	278	454	(164)	649
Hedged items	(232)	(461)	237	(626)
Income statement impact	46	(7)	73	23
Income statement impact of excluded components:
Amortization approach	0	0	0	0
Changes in fair value	49	(5)	67	29
OCI impact
Derivatives - Gains/(losses) recorded in OCI	$ 0	$ 0	$ 0	$ 0