ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Allowance for credit losses
Adjusted ACLL at beginning of year	$ 18,145	$ 16,974	$ 16,455
Gross credit losses on loans	(10,694)	(7,881)	(5,156)
Gross recoveries on loans	1,694	1,444	1,367
Net credit losses on loans (NCLs)	(9,000)	(6,437)	(3,789)
Net reserve builds (releases) for loans	791	1,272	937
Net specific reserve builds (releases) for loans	(65)	77	19
Total provision for credit losses on loans (PCLL)	9,726	7,786	4,745
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	23	0	0
Other, net	(320)	174	(437)
ACLL at end of year	18,574	18,145	16,974
Allowance for credit losses on unfunded commitments
Allowance for credit losses on unfunded commitments (ACLUC) at beginning of period	1,728	2,151	1,871
Provision (release) for credit losses on unfunded lending commitments	(119)	(425)	291
Other, net	(8)	2	(11)
ACLUC at end of period	1,601	1,728	2,151
Total allowance for credit losses on loans, leases and unfunded lending commitments	20,175	19,873	19,125
Sales or transfers of various consumer loan portfolios to held-for-sale
Purchased credit deteriorated assets	52	26
Financial instruments - TDRs and vintage disclosures
Allowance for credit losses
Adjusted ACLL at beginning of year		(352)
ACLL at end of year			(352)
Cumulative effect of adoption
Allowance for credit losses
Adjusted ACLL at beginning of year		(352)
ACLL at end of year			(352)
Adjusted balance
Allowance for credit losses
Adjusted ACLL at beginning of year		16,622
ACLL at end of year			16,622
Consumer
Allowance for credit losses
Adjusted ACLL at beginning of year	15,431	14,119	14,040
Gross credit losses on loans	(10,201)	(7,553)	(4,878)
Gross recoveries on loans	1,598	1,366	1,267
Net credit losses on loans (NCLs)	(8,603)	(6,187)	(3,611)
Net reserve builds (releases) for loans	858	1,440	563
Net specific reserve builds (releases) for loans	(2)	38	(46)
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	23
Other, net	(292)	186	(438)
ACLL at end of year	16,018	15,431	14,119
Sales or transfers of various consumer loan portfolios to held-for-sale
Reclasses of consumer ACLL to HFS	0	0	(350)
Consumer | Financial instruments - TDRs and vintage disclosures
Allowance for credit losses
Adjusted ACLL at beginning of year		(352)
ACLL at end of year			(352)
Consumer | Asia Consumer Loan
Sales or transfers of various consumer loan portfolios to held-for-sale
Reclass consumer to held-for sale	0	0	(350)
Consumer | Adjusted balance
Allowance for credit losses
Adjusted ACLL at beginning of year		13,767
ACLL at end of year			13,767
Corporate
Allowance for credit losses
Adjusted ACLL at beginning of year	2,714	2,855	2,415
Gross credit losses on loans	(493)	(328)	(278)
Gross recoveries on loans	96	78	100
Net credit losses on loans (NCLs)	(397)	(250)	(178)
Net reserve builds (releases) for loans	(67)	(168)	374
Net specific reserve builds (releases) for loans	(63)	39	65
Initial allowance for credit losses on newly purchased credit-deteriorated assets during the period	0
Other, net	(28)	(12)	1
ACLL at end of year	2,556	2,714	2,855
Sales or transfers of various consumer loan portfolios to held-for-sale
FX translation	$ (320)	174	(87)
Corporate | Financial instruments - TDRs and vintage disclosures
Allowance for credit losses
Adjusted ACLL at beginning of year		0
ACLL at end of year			0
Corporate | Adjusted balance
Allowance for credit losses
Adjusted ACLL at beginning of year		$ 2,855
ACLL at end of year			$ 2,855