LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	$ 645,960	$ 667,767
Loans at fair value	3,879	6,082
Corporate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	288,377	291,233
Total non-accrual	1,485	1,553
Loans at fair value	3,638	6,070
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	151,610	147,004
Total non-accrual	1,085	1,263
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	66,904	71,767
Total non-accrual	178	2
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	21,720	20,291
Total non-accrual	110	136
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	44,074	45,646
Total non-accrual	102	138
Corporate | Corporate loans, net of unearned income
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	84,703	90,549
One year prior to current fiscal year	23,698	17,944
Two years prior to current fiscal year	13,372	15,094
Three years prior to current fiscal year	11,064	13,278
Four years prior to current fiscal year	9,582	7,071
Prior	22,005	21,190
Revolving line of credit arrangements	120,315	120,037
Total loans, net of unearned income	288,377	291,233
Loans at fair value	3,638	6,070
Corporate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	61,775	66,744
One year prior to current fiscal year	16,633	13,966
Two years prior to current fiscal year	10,144	10,317
Three years prior to current fiscal year	8,262	9,599
Four years prior to current fiscal year	7,144	4,872
Prior	15,969	15,635
Revolving line of credit arrangements	99,356	93,086
Total loans, net of unearned income	219,283	214,219
Corporate | Investment grade | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	40,874	42,422
One year prior to current fiscal year	6,736	5,529
Two years prior to current fiscal year	3,544	4,642
Three years prior to current fiscal year	3,550	3,757
Four years prior to current fiscal year	2,771	2,911
Prior	7,943	8,392
Revolving line of credit arrangements	38,771	30,588
Total loans, net of unearned income	104,189	98,241
Corporate | Investment grade | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	10,942	12,862
One year prior to current fiscal year	4,787	1,678
Two years prior to current fiscal year	1,053	1,183
Three years prior to current fiscal year	1,104	1,038
Four years prior to current fiscal year	764	419
Prior	1,722	1,354
Revolving line of credit arrangements	37,679	43,630
Total loans, net of unearned income	58,051	62,164
Corporate | Investment grade | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,376	2,423
One year prior to current fiscal year	2,997	3,660
Two years prior to current fiscal year	3,858	3,332
Three years prior to current fiscal year	2,779	2,015
Four years prior to current fiscal year	1,393	1,212
Prior	2,083	1,288
Revolving line of credit arrangements	174	141
Total loans, net of unearned income	16,660	14,071
Corporate | Investment grade | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6,583	9,037
One year prior to current fiscal year	2,113	3,099
Two years prior to current fiscal year	1,689	1,160
Three years prior to current fiscal year	829	2,789
Four years prior to current fiscal year	2,216	330
Prior	4,221	4,601
Revolving line of credit arrangements	22,732	18,727
Total loans, net of unearned income	40,383	39,743
Corporate | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	22,928	23,805
One year prior to current fiscal year	7,065	3,978
Two years prior to current fiscal year	3,228	4,777
Three years prior to current fiscal year	2,802	3,679
Four years prior to current fiscal year	2,438	2,199
Prior	6,036	5,555
Revolving line of credit arrangements	20,959	26,951
Total loans, net of unearned income	65,456	70,944
Corporate | Non-investment grade, accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	16,582	16,783
One year prior to current fiscal year	4,509	2,281
Two years prior to current fiscal year	1,858	2,343
Three years prior to current fiscal year	1,275	2,024
Four years prior to current fiscal year	1,134	1,412
Prior	4,267	3,981
Revolving line of credit arrangements	16,711	18,676
Total loans, net of unearned income	46,336	47,500
Corporate | Non-investment grade, accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	4,674	4,325
One year prior to current fiscal year	1,006	347
Two years prior to current fiscal year	217	567
Three years prior to current fiscal year	232	101
Four years prior to current fiscal year	53	71
Prior	423	511
Revolving line of credit arrangements	2,070	3,679
Total loans, net of unearned income	8,675	9,601
Corporate | Non-investment grade, accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	532	1,275
One year prior to current fiscal year	761	869
Two years prior to current fiscal year	513	1,228
Three years prior to current fiscal year	782	1,018
Four years prior to current fiscal year	1,049	493
Prior	865	586
Revolving line of credit arrangements	448	615
Total loans, net of unearned income	4,950	6,084
Corporate | Non-investment grade, accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	929	1,339
One year prior to current fiscal year	615	349
Two years prior to current fiscal year	493	554
Three years prior to current fiscal year	394	364
Four years prior to current fiscal year	121	119
Prior	306	245
Revolving line of credit arrangements	1,152	3,236
Total loans, net of unearned income	4,010	6,206
Corporate | Non-investment grade, non-accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	157	53
One year prior to current fiscal year	107	119
Two years prior to current fiscal year	111	64
Three years prior to current fiscal year	81	104
Four years prior to current fiscal year	71	94
Prior	147	117
Revolving line of credit arrangements	411	712
Total non-accrual	1,085	1,263
Corporate | Non-investment grade, non-accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	41	0
One year prior to current fiscal year	35	0
Two years prior to current fiscal year	0	0
Three years prior to current fiscal year	0	0
Four years prior to current fiscal year	0	0
Prior	0	0
Revolving line of credit arrangements	102	2
Total non-accrual	178	2
Corporate | Non-investment grade, non-accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	11
One year prior to current fiscal year	31	8
Two years prior to current fiscal year	28	2
Three years prior to current fiscal year	0	49
Four years prior to current fiscal year	0	10
Prior	15	25
Revolving line of credit arrangements	36	31
Total non-accrual	110	136
Corporate | Non-investment grade, non-accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	13	19
One year prior to current fiscal year	1	5
Two years prior to current fiscal year	8	19
Three years prior to current fiscal year	38	19
Four years prior to current fiscal year	10	0
Prior	13	90
Revolving line of credit arrangements	29	0
Total non-accrual	$ 112	$ 152