INCOME TAXES - Components of Income Tax Provision (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal										$ 332	$ 1,016	$ 861
Non-U.S.										3,910	3,585	3,397
State										269	384	388
Total current income taxes										4,511	4,985	4,646
Deferred
Federal										24,902	1,280	3,019
Non-U.S.										(377)	53	(4)
State										352	126	(221)
Total deferred income taxes	[1]									24,877	1,459	2,794
Provision for income tax on continuing operations before non-controlling interests		$ 23,864	$ 1,866	$ 1,795	$ 1,863	$ 1,509	$ 1,733	$ 1,723	$ 1,479	29,388	6,444	7,440
Provision (benefit) for income taxes on discontinued operations										7	(22)	(29)
Income tax expense (benefit) reported in stockholders’ equity related to:
FX translation										188	(402)	(906)
Investment securities										(149)	59	(498)
Employee stock plans										(4)	13	(35)
Cash flow hedges										(12)	27	176
Benefit plans										13	(30)	(24)
FVO DVA										(250)	(201)	0
Retained earnings										(295)	0	0
Income taxes before non-controlling interests										28,886	5,888	6,124
Provision (benefit) for effect of securities transactions										272	332	239
Benefit for effect of other-than-temporary-impairment losses										$ (22)	$ (217)	$ (93)

[1] Includes the full impact of the $22.6 billion non-cash charge related to the Tax Cuts and Jobs Act (Tax Reform). See Notes 1 and 9 to the Consolidated Financial Statements for further information.