LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Loans receivable
Loans, net of unearned income	$ 689,362	$ 657,221
Loans	7,594	5,360
Corporate
Loans receivable
Loans, net of unearned income	300,165	289,154
Loans	7,281	5,123
Corporate | Corporate loans, net of unearned income
Loans receivable
2023	90,737	88,444
2022	27,788	21,137
2021	15,899	13,019
2020	8,869	10,492
2019	7,313	8,051
Prior	20,008	18,854
Revolving line of credit arrangements	122,177	124,034
Loans, net of unearned income	300,072	289,154
Loans	7,281	5,123
Corporate | Investment Grade
Loans receivable
2023	67,094	64,574
2022	20,308	15,924
2021	11,142	9,904
2020	6,276	7,642
2019	5,211	6,196
Prior	15,638	13,913
Revolving line of credit arrangements	101,072	102,777
Loans, net of unearned income	226,741	220,930
Corporate | Investment Grade | Commercial and industrial
Loans receivable
2023	47,811	40,639
2022	7,738	6,124
2021	3,641	3,620
2020	2,279	3,458
2019	2,604	2,617
Prior	6,907	7,048
Revolving line of credit arrangements	34,956	38,358
Loans, net of unearned income	105,936	101,864
Corporate | Investment Grade | Financial institutions
Loans receivable
2023	11,002	11,850
2022	2,356	3,877
2021	2,834	835
2020	424	922
2019	557	333
Prior	1,847	1,327
Revolving line of credit arrangements	36,715	37,462
Loans, net of unearned income	55,735	56,606
Corporate | Investment Grade | Mortgage and real estate
Loans receivable
2023	3,628	4,436
2022	4,433	3,236
2021	3,595	4,010
2020	2,544	2,619
2019	1,238	1,127
Prior	1,582	1,706
Revolving line of credit arrangements	66	152
Loans, net of unearned income	17,086	17,286
Corporate | Investment Grade | Other
Loans receivable
2023	4,653	7,649
2022	5,781	2,687
2021	1,072	1,439
2020	1,029	643
2019	812	2,119
Prior	5,302	3,832
Revolving line of credit arrangements	29,335	26,805
Loans, net of unearned income	47,984	45,174
Corporate | Non-investment grade, accrual | Commercial and industrial
Loans receivable
2023	17,570	17,278
2022	4,785	3,139
2021	1,914	1,973
2020	1,359	1,331
2019	732	965
Prior	2,526	3,546
Revolving line of credit arrangements	15,912	16,848
Loans, net of unearned income	44,798	45,080
Corporate | Non-investment grade, accrual | Financial institutions
Loans receivable
2023	4,207	4,708
2022	748	630
2021	1,084	197
2020	56	254
2019	194	47
Prior	260	240
Revolving line of credit arrangements	2,725	2,073
Loans, net of unearned income	9,274	8,149
Corporate | Non-investment grade, accrual | Mortgage and real estate
Loans receivable
2023	1,034	582
2022	1,234	835
2021	1,378	429
2020	947	729
2019	755	783
Prior	1,016	801
Revolving line of credit arrangements	620	472
Loans, net of unearned income	6,984	4,631
Corporate | Non-investment grade, accrual | Other
Loans receivable
2023	653	1,244
2022	434	559
2021	248	391
2020	158	413
2019	211	1
Prior	155	219
Revolving line of credit arrangements	1,253	1,292
Loans, net of unearned income	3,112	4,119
Corporate | Non-investment grade, non-accrual | Commercial and industrial
Loans receivable
2023	53	1
2022	46	12
2021	84	99
2020	35	115
2019	45	49
Prior	93	105
Revolving line of credit arrangements	361	479
Financing receivable, nonaccrual	717	860
Corporate | Non-investment grade, non-accrual | Financial institutions
Loans receivable
2023	0	41
2022	0	34
2021	0	0
2020	0	0
2019	0	0
Prior	0	0
Revolving line of credit arrangements	51	77
Financing receivable, nonaccrual	51	152
Corporate | Non-investment grade, non-accrual | Mortgage and real estate
Loans receivable
2023	118	10
2022	233	4
2021	8	0
2020	38	0
2019	110	0
Prior	308	19
Revolving line of credit arrangements	53	0
Financing receivable, nonaccrual	868	33
Corporate | Non-investment grade, non-accrual | Other
Loans receivable
2023	8	6
2022	0	0
2021	41	26
2020	0	8
2019	55	10
Prior	12	11
Revolving line of credit arrangements	130	16
Financing receivable, nonaccrual	246	77
Corporate | Non-Investment Grade
Loans receivable
2023	23,643	23,870
2022	7,480	5,213
2021	4,757	3,115
2020	2,593	2,850
2019	2,102	1,855
Prior	4,370	4,941
Revolving line of credit arrangements	21,105	21,257
Loans, net of unearned income	$ 66,050	$ 63,101