ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses Roll Forward by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	$ 17,496	$ 15,952	$ 16,974	$ 16,455
Charge-offs	(2,000)	(1,237)	(5,513)	(3,689)
Recoveries	363	350	1,070	1,080
Replenishment of NCLs	1,637	887	4,443	2,609
Net reserve builds (releases)	100	519	787	259
Net specific reserve builds (releases)	79	(78)	84	104
Other	(46)	(84)	136	(509)
ACLL at end of period	17,629	16,309	17,629	16,309
ACLL
Collectively evaluated	17,219		17,219		$ 16,053
Individually evaluated	410		410		919
Total ACLL	17,629	16,309	17,629	16,309	16,974
Loans, net of unearned income
Collectively evaluated	656,790		656,790		647,704
Individually evaluated	2,033		2,033		4,043
Held at fair value	7,411		7,411		5,360
Total loans, net of unearned income	666,348		666,348		657,221
Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	0	0	(352)	0
ACLL
Total ACLL					(352)
Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	17,496	15,952	16,622	16,455
ACLL
Total ACLL					16,622
Purchased credit deteriorated
ACLL
Purchased credit deteriorated	0		0		2
Loans, net of unearned income
Purchased credit deteriorated	114		114		114
Corporate loans
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period	2,630	2,969	2,855	2,415
Charge-offs	(72)	(43)	(197)	(148)
Recoveries	14	37	42	88
Replenishment of NCLs	58	6	155	60
Net reserve builds (releases)	25	145	(184)	394
Net specific reserve builds (releases)	77	(104)	49	169
Other	(15)	(62)	(3)	(30)
ACLL at end of period	2,717	2,948	2,717	2,948
ACLL
Collectively evaluated	2,347		2,347		2,532
Individually evaluated	370		370		323
Total ACLL	2,717	2,948	2,717	2,948	2,855
Loans, net of unearned income
Collectively evaluated	279,470		279,470		282,909
Individually evaluated	1,975		1,975		1,122
Held at fair value	7,189		7,189		5,123
Total loans, net of unearned income	288,634		288,634		289,154
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			2,855	2,415
ACLL
Total ACLL					2,855
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	14,866	12,983	14,119	14,040
Charge-offs	(1,928)	(1,194)	(5,316)	(3,541)
Recoveries	349	313	1,028	992
Replenishment of NCLs	1,579	881	4,288	2,549
Net reserve builds (releases)	75	374	971	(135)
Net specific reserve builds (releases)	2	26	35	(65)
Other	(31)	(22)	139	(479)
ACLL at end of period	14,912	13,361	14,912	13,361
ACLL
Collectively evaluated	14,872		14,872		13,521
Individually evaluated	40		40		596
Total ACLL	14,912	$ 13,361	14,912	13,361	14,119
Loans, net of unearned income
Collectively evaluated	377,320		377,320		364,795
Individually evaluated	58		58		2,921
Held at fair value	222		222		237
Total loans, net of unearned income	377,714		377,714		368,067
Consumer loans | Cumulative Effect, Period of Adoption, Adjustment
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period			(352)	0
ACLL
Total ACLL					(352)
Consumer loans | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for credit losses
Allowance for credit losses on loans (ACLL) at beginning of period			13,767	$ 14,040
ACLL
Total ACLL					13,767
Consumer loans | Purchased credit deteriorated
ACLL
Purchased credit deteriorated	0		0		2
Loans, net of unearned income
Purchased credit deteriorated	$ 114		$ 114		$ 114