ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	$ 19,123	$ 18,216	$ 18,574	$ 18,145
Gross credit losses on loans	(2,726)	(2,609)	(8,375)	(8,014)
Gross recoveries on loans	512	437	1,468	1,256
Net credit losses (NCLs) on loans	(2,214)	(2,172)	(6,907)	(6,758)
Net reserve builds (releases) for loans	(10)	254	466	636
Net specific reserve builds (releases) for loans	55	(44)	(76)	(231)
Total provision for credit losses on loans (PCLL)	2,259	2,382	7,297	7,163
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	0	23	0	23
Other, net (see table below)	38	(93)	242	(217)
ACLL at end of period	19,206	18,356	19,206	18,356
Allowance for credit losses on unfunded commitments
Allowance for credit losses on unfunded commitments (ACLUC) at beginning of period	1,721	1,619	1,601	1,728
Provision (release) for credit losses on unfunded lending commitments	100	105	189	(1)
Other, net	(1)	1	30	(2)
ACLUC at end of period	1,820	1,725	1,820	1,725
Total ACLL and ACLUC	21,026	20,081	21,026	20,081
Allowance for credit losses on other assets
Allowance for credit losses on other assets at beginning of quarter	2,699	1,911	1,865	1,788
NCLs on other assets	(7)	(6)	(25)	(21)
Provision for credit losses on other assets	79	110	499	226
Other, net	(150)	(146)	282	(124)
Allowance for credit losses on other assets at end of quarter	2,621	1,869	2,621	1,869
Allowance for credit losses on HTM debt securities
Allowance for credit losses on HTM debt securities at beginning of period	136	99	137	95
Provision (release) for credit losses on HTM debt securities	(5)	50	(3)	55
Other, net	0	(8)	(3)	(9)
Allowance for credit losses on HTM debt securities at end of period	131	141	131	141
Total ACL	23,778	22,091	23,778	22,091	$ 22,177
Sales or transfers of various consumer loan portfolios to HFS
Reclasses of consumer ACLL to HFS	0	0	(29)	0
FX translation and other	38	(93)	271	(217)
Other, net (ACLL)	38	(93)	242	(217)
Corporate loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	3,023	2,484	2,556	2,714
Gross credit losses on loans	(114)	(113)	(376)	(420)
Gross recoveries on loans	22	39	53	74
Net credit losses (NCLs) on loans	(92)	(74)	(323)	(346)
Net reserve builds (releases) for loans	(76)	143	468	115
Net specific reserve builds (releases) for loans	54	(40)	(77)	(229)
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	0	0	0	0
Other, net (see table below)	0	4	54	(9)
ACLL at end of period	3,001	2,591	3,001	2,591
Sales or transfers of various consumer loan portfolios to HFS
Other, net (ACLL)	0	4	54	(9)
Consumer loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	16,100	15,732	16,018	15,431
Gross credit losses on loans	(2,612)	(2,496)	(7,999)	(7,594)
Gross recoveries on loans	490	398	1,415	1,182
Net credit losses (NCLs) on loans	(2,122)	(2,098)	(6,584)	(6,412)
Net reserve builds (releases) for loans	66	111	(2)	521
Net specific reserve builds (releases) for loans	1	(4)	1	(2)
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	0	23	0	23
Other, net (see table below)	38	(97)	188	(208)
ACLL at end of period	16,205	15,765	16,205	15,765
Sales or transfers of various consumer loan portfolios to HFS
Other, net (ACLL)	$ 38	$ (97)	$ 188	$ (208)