ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	$ 18,296	$ 17,169	$ 18,145	$ 16,974
Charge-offs	(2,715)	(1,879)	(5,405)	(3,513)
Recoveries	432	375	819	707
Replenishment of NCLs	2,283	1,504	4,586	2,806
Net reserve builds (releases)	136	290	382	687
Net specific reserve builds (releases)	(60)	(33)	(187)	5
Other	(156)	70	(124)	182
ACLL at end of period	18,216	17,496	18,216	17,496
ACLL
Collectively evaluated	18,003		18,003		$ 17,743
Individually evaluated	213		213		402
Total ACLL	18,216	17,496	18,216	17,496	18,145
Loans, net of unearned income
Collectively evaluated	678,026		678,026		679,713
Individually evaluated	1,058		1,058		1,940
Held at fair value	8,526		8,526		7,594
Total loans, net of unearned income	687,722		687,722		689,362
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	18,296	17,169	18,145	16,622
ACLL
Total ACLL					18,145
Purchased credit deteriorated
ACLL
Purchased credit deteriorated	0		0		0
Loans, net of unearned income
Purchased credit deteriorated	112		112		115
Corporate loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	2,772	2,780	2,714	2,855
Charge-offs	(129)	(86)	(307)	(125)
Recoveries	21	11	35	28
Replenishment of NCLs	108	75	272	97
Net reserve builds (releases)	(216)	(119)	(28)	(209)
Net specific reserve builds (releases)	(58)	(33)	(189)	(28)
Other	(14)	2	(13)	12
ACLL at end of period	2,484	2,630	2,484	2,630
ACLL
Collectively evaluated	2,313		2,313		2,352
Individually evaluated	171		171		362
Total ACLL	2,484	2,630	2,484	2,630	2,714
Loans, net of unearned income
Collectively evaluated	292,375		292,375		291,002
Individually evaluated	998		998		1,882
Held at fair value	8,232		8,232		7,281
Total loans, net of unearned income	301,605		301,605		300,165
Corporate loans | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period			0	0
ACLL
Total ACLL					0
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	15,524	14,389	15,431	14,119
Charge-offs	(2,586)	(1,793)	(5,098)	(3,388)
Recoveries	411	364	784	679
Replenishment of NCLs	2,175	1,429	4,314	2,709
Net reserve builds (releases)	352	409	410	896
Net specific reserve builds (releases)	(2)	0	2	33
Other	(142)	68	(111)	170
ACLL at end of period	15,732	14,866	15,732	14,866
ACLL
Collectively evaluated	15,690		15,690		15,391
Individually evaluated	42		42		40
Total ACLL	15,732	$ 14,866	15,732	14,866	15,431
Loans, net of unearned income
Collectively evaluated	385,651		385,651		388,711
Individually evaluated	60		60		58
Held at fair value	294		294		313
Total loans, net of unearned income	386,117		386,117		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			0	(352)
ACLL
Total ACLL					0
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	0		0		0
Loans, net of unearned income
Purchased credit deteriorated	$ 112		$ 112		$ 115