LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 660,612	$ 657,221
Loans at fair value	5,766	5,360
Corporate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	286,021	289,154
Total non-accrual	1,261	1,122
Loans at fair value	5,529	5,123
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	152,591	147,803
Total non-accrual	856	860
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	57,594	64,907
Total non-accrual	93	152
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	23,501	21,949
Total non-accrual	291	33
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	46,533	49,018
Total non-accrual	21	67
Corporate | Corporate loans, net of unearned income
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	69,004	88,444
One year prior to current fiscal year	33,351	21,137
Two years prior to current fiscal year	18,824	13,019
Three years prior to current fiscal year	10,566	10,492
Four years prior to current fiscal year	9,113	8,051
Prior	23,174	18,854
Revolving line of credit arrangements	116,460	124,034
Loans, net of unearned income	286,021	289,154
Loans at fair value	5,529	5,123
Corporate | Corporate loans, net of unearned income | Revision of Prior Period, Adjustment
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year		(24,900)
One year prior to current fiscal year		2,000
Two years prior to current fiscal year		3,200
Three years prior to current fiscal year		4,600
Four years prior to current fiscal year		4,100
Prior		11,000
Corporate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	50,336	64,574
One year prior to current fiscal year	24,003	15,924
Two years prior to current fiscal year	14,188	9,904
Three years prior to current fiscal year	7,978	7,642
Four years prior to current fiscal year	6,384	6,196
Prior	17,558	13,913
Revolving line of credit arrangements	95,176	102,777
Loans, net of unearned income	215,623	220,930
Corporate | Investment grade | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	40,041	40,639
One year prior to current fiscal year	8,089	6,124
Two years prior to current fiscal year	5,285	3,620
Three years prior to current fiscal year	2,809	3,458
Four years prior to current fiscal year	3,151	2,617
Prior	8,415	7,048
Revolving line of credit arrangements	37,929	38,358
Loans, net of unearned income	105,719	101,864
Corporate | Investment grade | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6,390	11,850
One year prior to current fiscal year	4,490	3,877
Two years prior to current fiscal year	3,816	835
Three years prior to current fiscal year	572	922
Four years prior to current fiscal year	708	333
Prior	2,087	1,327
Revolving line of credit arrangements	30,865	37,462
Loans, net of unearned income	48,928	56,606
Corporate | Investment grade | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,731	4,436
One year prior to current fiscal year	4,803	3,236
Two years prior to current fiscal year	3,752	4,010
Three years prior to current fiscal year	3,639	2,619
Four years prior to current fiscal year	1,791	1,127
Prior	2,259	1,706
Revolving line of credit arrangements	131	152
Loans, net of unearned income	18,106	17,286
Corporate | Investment grade | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,174	7,649
One year prior to current fiscal year	6,621	2,687
Two years prior to current fiscal year	1,335	1,439
Three years prior to current fiscal year	958	643
Four years prior to current fiscal year	734	2,119
Prior	4,797	3,832
Revolving line of credit arrangements	26,251	26,805
Loans, net of unearned income	42,870	45,174
Corporate | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	18,668	23,870
One year prior to current fiscal year	9,348	5,213
Two years prior to current fiscal year	4,636	3,115
Three years prior to current fiscal year	2,588	2,850
Four years prior to current fiscal year	2,729	1,855
Prior	5,616	4,941
Revolving line of credit arrangements	21,284	21,257
Loans, net of unearned income	64,869	63,101
Corporate | Non-investment grade, accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	14,071	17,278
One year prior to current fiscal year	6,408	3,139
Two years prior to current fiscal year	2,351	1,973
Three years prior to current fiscal year	1,666	1,331
Four years prior to current fiscal year	907	965
Prior	3,657	3,546
Revolving line of credit arrangements	16,956	16,848
Loans, net of unearned income	46,016	45,080
Corporate | Non-investment grade, accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,421	4,708
One year prior to current fiscal year	1,552	630
Two years prior to current fiscal year	892	197
Three years prior to current fiscal year	23	254
Four years prior to current fiscal year	437	47
Prior	176	240
Revolving line of credit arrangements	2,072	2,073
Loans, net of unearned income	8,573	8,149
Corporate | Non-investment grade, accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	608	582
One year prior to current fiscal year	544	835
Two years prior to current fiscal year	782	429
Three years prior to current fiscal year	510	729
Four years prior to current fiscal year	725	783
Prior	1,419	801
Revolving line of credit arrangements	516	472
Loans, net of unearned income	5,104	4,631
Corporate | Non-investment grade, accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	559	1,244
One year prior to current fiscal year	756	559
Two years prior to current fiscal year	478	391
Three years prior to current fiscal year	372	413
Four years prior to current fiscal year	497	1
Prior	108	219
Revolving line of credit arrangements	1,145	1,292
Loans, net of unearned income	3,915	4,119
Corporate | Non-investment grade, non-accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	5	1
One year prior to current fiscal year	81	12
Two years prior to current fiscal year	59	99
Three years prior to current fiscal year	9	115
Four years prior to current fiscal year	52	49
Prior	159	105
Revolving line of credit arrangements	491	479
Total non-accrual	856	860
Corporate | Non-investment grade, non-accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	41
One year prior to current fiscal year	3	34
Two years prior to current fiscal year	35	0
Three years prior to current fiscal year	0	0
Four years prior to current fiscal year	8	0
Prior	0	0
Revolving line of credit arrangements	47	77
Total non-accrual	93	152
Corporate | Non-investment grade, non-accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3	10
One year prior to current fiscal year	0	4
Two years prior to current fiscal year	38	0
Three years prior to current fiscal year	8	0
Four years prior to current fiscal year	103	0
Prior	86	19
Revolving line of credit arrangements	53	0
Total non-accrual	291	33
Corporate | Non-investment grade, non-accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	6
One year prior to current fiscal year	4	0
Two years prior to current fiscal year	1	26
Three years prior to current fiscal year	0	8
Four years prior to current fiscal year	0	10
Prior	11	11
Revolving line of credit arrangements	4	16
Total non-accrual	$ 21	$ 77