ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	$ 18,216	$ 17,496	$ 18,145	$ 16,974
Charge-offs	(2,609)	(2,000)	(8,014)	(5,513)
Recoveries	437	363	1,256	1,070
Replenishment of NCLs	2,172	1,637	6,758	4,443
Net reserve builds (releases)	254	100	636	787
Net specific reserve builds (releases)	(44)	79	(231)	84
Other	(93)	(46)	(217)	136
ACLL at end of period	18,356	17,629	18,356	17,629
ACLL
Collectively evaluated	18,155		18,155		$ 17,743
Individually evaluated	179		179		402
Total ACLL	18,356	17,629	18,356	17,629	18,145
Loans, net of unearned income
Collectively evaluated	679,668		679,668		679,713
Individually evaluated	1,004		1,004		1,940
Held at fair value	8,106		8,106		7,594
Total loans, net of unearned income	688,922		688,922		689,362
Credit deteriorated assets, par value	37	6	46	19
Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period				(352)
ACLL
Total ACLL
Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	18,216	17,496	18,145	16,622
ACLL
Total ACLL					18,145
Purchased credit deteriorated
ACLL
Purchased credit deteriorated	22		22		0
Loans, net of unearned income
Purchased credit deteriorated	144		144		115
Corporate loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	2,484	2,630	2,714	2,855
Charge-offs	(113)	(72)	(420)	(197)
Recoveries	39	14	74	42
Replenishment of NCLs	74	58	346	155
Net reserve builds (releases)	143	25	115	(184)
Net specific reserve builds (releases)	(40)	77	(229)	49
Other	4	(15)	(9)	(3)
ACLL at end of period	2,591	2,717	2,591	2,717
ACLL
Collectively evaluated	2,451		2,451		2,352
Individually evaluated	140		140		362
Total ACLL	2,591	2,717	2,591	2,717	2,714
Loans, net of unearned income
Collectively evaluated	291,023		291,023		291,002
Individually evaluated	944		944		1,882
Held at fair value	7,804		7,804		7,281
Total loans, net of unearned income	299,771		299,771		300,165
Corporate loans | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period			2,714	2,855
ACLL
Total ACLL					2,714
Corporate loans | Purchased credit deteriorated
ACLL
Purchased credit deteriorated	0		0		0
Loans, net of unearned income
Purchased credit deteriorated	0		0		0
Consumer loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	15,732	14,866	15,431	14,119
Charge-offs	(2,496)	(1,928)	(7,594)	(5,316)
Recoveries	398	349	1,182	1,028
Replenishment of NCLs	2,098	1,579	6,412	4,288
Net reserve builds (releases)	111	75	521	971
Net specific reserve builds (releases)	(4)	2	(2)	35
Other	(97)	(31)	(208)	139
ACLL at end of period	15,765	14,912	15,765	14,912
ACLL
Collectively evaluated	15,704		15,704		15,391
Individually evaluated	39		39		40
Total ACLL	15,765	$ 14,912	15,765	14,912	15,431
Loans, net of unearned income
Collectively evaluated	388,645		388,645		388,711
Individually evaluated	60		60		58
Held at fair value	302		302		313
Total loans, net of unearned income	389,151		389,151		389,197
Consumer loans | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period				(352)
ACLL
Total ACLL
Consumer loans | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period			15,431	$ 13,767
ACLL
Total ACLL					15,431
Consumer loans | Purchased credit deteriorated
ACLL
Purchased credit deteriorated	22		22		0
Loans, net of unearned income
Purchased credit deteriorated	$ 144		$ 144		$ 115