LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	$ 657,333	$ 667,767
Loans at fair value	4,536	6,082
Corporate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	301,728	291,233
Total non-accrual	1,655	1,553
Loans at fair value	4,528	6,070
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	161,338	147,004
Total non-accrual	1,407	1,263
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	70,448	71,767
Total non-accrual	78	2
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	21,761	20,291
Total non-accrual	77	136
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	43,221	45,646
Total non-accrual	82	138
Corporate | Corporate loans, net of unearned income
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	81,304	90,549
One year prior to current fiscal year	28,459	17,944
Two years prior to current fiscal year	15,477	15,094
Three years prior to current fiscal year	12,857	13,278
Four years prior to current fiscal year	10,799	7,071
Prior	25,249	21,190
Revolving line of credit arrangements	123,055	120,037
Total loans, net of unearned income	301,728	291,233
Loans at fair value	4,528	6,070
Corporate | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	60,884	66,744
One year prior to current fiscal year	19,752	13,966
Two years prior to current fiscal year	11,848	10,317
Three years prior to current fiscal year	9,464	9,599
Four years prior to current fiscal year	7,913	4,872
Prior	18,528	15,635
Revolving line of credit arrangements	98,071	93,086
Total loans, net of unearned income	226,460	214,219
Corporate | Investment grade | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	43,233	42,422
One year prior to current fiscal year	7,890	5,529
Two years prior to current fiscal year	4,305	4,642
Three years prior to current fiscal year	4,009	3,757
Four years prior to current fiscal year	3,268	2,911
Prior	9,500	8,392
Revolving line of credit arrangements	39,383	30,588
Total loans, net of unearned income	111,588	98,241
Corporate | Investment grade | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	9,239	12,862
One year prior to current fiscal year	5,787	1,678
Two years prior to current fiscal year	1,434	1,183
Three years prior to current fiscal year	1,172	1,038
Four years prior to current fiscal year	828	419
Prior	1,636	1,354
Revolving line of credit arrangements	39,935	43,630
Total loans, net of unearned income	60,031	62,164
Corporate | Investment grade | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,363	2,423
One year prior to current fiscal year	3,323	3,660
Two years prior to current fiscal year	3,881	3,332
Three years prior to current fiscal year	3,256	2,015
Four years prior to current fiscal year	1,640	1,212
Prior	2,148	1,288
Revolving line of credit arrangements	277	141
Total loans, net of unearned income	16,888	14,071
Corporate | Investment grade | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6,049	9,037
One year prior to current fiscal year	2,752	3,099
Two years prior to current fiscal year	2,228	1,160
Three years prior to current fiscal year	1,027	2,789
Four years prior to current fiscal year	2,177	330
Prior	5,244	4,601
Revolving line of credit arrangements	18,476	18,727
Total loans, net of unearned income	37,953	39,743
Corporate | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20,420	23,805
One year prior to current fiscal year	8,707	3,978
Two years prior to current fiscal year	3,629	4,777
Three years prior to current fiscal year	3,393	3,679
Four years prior to current fiscal year	2,886	2,199
Prior	6,721	5,555
Revolving line of credit arrangements	24,984	26,951
Total loans, net of unearned income	70,740	70,944
Corporate | Non-investment grade, accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	14,009	16,783
One year prior to current fiscal year	5,880	2,281
Two years prior to current fiscal year	2,167	2,343
Three years prior to current fiscal year	1,601	2,024
Four years prior to current fiscal year	1,511	1,412
Prior	4,752	3,981
Revolving line of credit arrangements	18,423	18,676
Total loans, net of unearned income	48,343	47,500
Corporate | Non-investment grade, accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	5,092	4,325
One year prior to current fiscal year	1,111	347
Two years prior to current fiscal year	252	567
Three years prior to current fiscal year	341	101
Four years prior to current fiscal year	57	71
Prior	494	511
Revolving line of credit arrangements	2,992	3,679
Total loans, net of unearned income	10,339	9,601
Corporate | Non-investment grade, accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	196	1,275
One year prior to current fiscal year	853	869
Two years prior to current fiscal year	519	1,228
Three years prior to current fiscal year	860	1,018
Four years prior to current fiscal year	995	493
Prior	994	586
Revolving line of credit arrangements	379	615
Total loans, net of unearned income	4,796	6,084
Corporate | Non-investment grade, accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	886	1,339
One year prior to current fiscal year	712	349
Two years prior to current fiscal year	374	554
Three years prior to current fiscal year	449	364
Four years prior to current fiscal year	224	119
Prior	298	245
Revolving line of credit arrangements	2,664	3,236
Total loans, net of unearned income	5,607	6,206
Corporate | Non-investment grade, non-accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	160	53
One year prior to current fiscal year	110	119
Two years prior to current fiscal year	313	64
Three years prior to current fiscal year	133	104
Four years prior to current fiscal year	82	94
Prior	148	117
Revolving line of credit arrangements	461	712
Total non-accrual	1,407	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	2	2
Total non-accrual	78	2
Corporate | Non-investment grade, non-accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6	11
One year prior to current fiscal year	1	8
Two years prior to current fiscal year	1	2
Three years prior to current fiscal year	0	49
Four years prior to current fiscal year	0	10
Prior	23	25
Revolving line of credit arrangements	46	31
Total non-accrual	77	136
Corporate | Non-investment grade, non-accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	30	19
One year prior to current fiscal year	5	5
Two years prior to current fiscal year	3	19
Three years prior to current fiscal year	9	19
Four years prior to current fiscal year	17	0
Prior	12	90
Revolving line of credit arrangements	17	0
Total non-accrual	$ 93	$ 152