INCOME TAXES - Components of Income Tax Provision (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal										$ 834	$ 332	$ 1,016
Non-U.S.										4,290	3,910	3,585
State										284	269	384
Total current income taxes										5,408	4,511	4,985
Deferred
Federal										(620)	24,902	1,280
Non-U.S.										371	(377)	53
State										198	352	126
Total deferred income taxes	[1]									(51)	24,877	1,459
Provision for income tax on continuing operations before non-controlling interests		$ 1,001	$ 1,471	$ 1,444	$ 1,441	$ 23,864	$ 1,866	$ 1,795	$ 1,863	5,357	29,388	6,444
Provision (benefit) for income taxes on discontinued operations										(18)	7	(22)
Income tax expense (benefit) reported in stockholders’ equity related to:
FX translation										(263)	188	(402)
Investment securities										(346)	(149)	59
Employee stock plans										(2)	(4)	13
Cash flow hedges										(8)	(12)	27
Benefit plans										(20)	13	(30)
FVO DVA										302	(250)	(201)
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), after Adjustments, Tax, Parent										(17)	0	0
Retained earnings										(305)	(295)	0
Income taxes before noncontrolling interests										4,680	28,886	5,888
Provision (benefit) for effect of securities transactions										104	272	332
Benefit for effect of other-than-temporary-impairment losses										$ (32)	$ (22)	$ (217)

[1] Includes the full impact of the $22.6 billion non-cash charge related to the Tax Cuts and Jobs Act (Tax Reform) in 2017. See Notes 1 and 9 to the Consolidated Financial Statements for further information.