LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 702,056	$ 694,488
Loans at fair value	8,165	8,040
Unallocated portfolio layer cumulative basis adjustments		(72)
Corporate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	58,344	91,339
One year prior to current fiscal year	47,733	24,201
Two years prior to current fiscal year	24,369	19,849
Three years prior to current fiscal year	20,875	10,274
Four years prior to current fiscal year	8,832	5,460
Prior	21,636	18,185
Revolving line of credit arrangements	126,048	124,391
Loans, net of unearned income	315,744	301,386
Loans at fair value	7,887	7,759
Loans net of unearned income, before adjustments	315,724	301,458
Unallocated portfolio layer cumulative basis adjustments	20	(72)
Corporate loans | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	38,261	60,211
One year prior to current fiscal year	33,141	16,807
Two years prior to current fiscal year	16,728	13,502
Three years prior to current fiscal year	15,291	6,177
Four years prior to current fiscal year	5,284	4,106
Prior	16,105	13,464
Revolving line of credit arrangements	98,783	99,148
Loans, net of unearned income	223,593	213,415
Corporate loans | Investment grade | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	28,855	36,039
One year prior to current fiscal year	14,040	8,101
Two years prior to current fiscal year	7,665	5,035
Three years prior to current fiscal year	4,928	2,492
Four years prior to current fiscal year	2,092	1,225
Prior	5,798	4,853
Revolving line of credit arrangements	32,984	32,862
Loans, net of unearned income	96,362	90,607
Corporate loans | Investment grade | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6,584	13,074
One year prior to current fiscal year	8,182	2,136
Two years prior to current fiscal year	2,364	1,162
Three years prior to current fiscal year	3,275	326
Four years prior to current fiscal year	410	265
Prior	1,606	1,500
Revolving line of credit arrangements	41,961	41,415
Loans, net of unearned income	64,382	59,878
Corporate loans | Investment grade | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,090	5,325
One year prior to current fiscal year	5,266	3,927
Two years prior to current fiscal year	3,853	3,269
Three years prior to current fiscal year	3,219	2,537
Four years prior to current fiscal year	2,011	1,460
Prior	2,687	1,533
Revolving line of credit arrangements	249	248
Loans, net of unearned income	18,375	18,299
Corporate loans | Investment grade | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,732	5,773
One year prior to current fiscal year	5,653	2,643
Two years prior to current fiscal year	2,846	4,036
Three years prior to current fiscal year	3,869	822
Four years prior to current fiscal year	771	1,156
Prior	6,014	5,578
Revolving line of credit arrangements	23,589	24,623
Loans, net of unearned income	44,474	44,631
Corporate loans | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20,083	31,128
One year prior to current fiscal year	14,592	7,395
Two years prior to current fiscal year	7,641	6,347
Three years prior to current fiscal year	5,584	4,096
Four years prior to current fiscal year	3,548	1,354
Prior	5,531	4,721
Revolving line of credit arrangements	27,265	25,243
Loans, net of unearned income	84,244	80,284
Corporate loans | Non-investment grade, accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	16,122	24,937
One year prior to current fiscal year	10,722	5,082
Two years prior to current fiscal year	5,185	3,576
Three years prior to current fiscal year	3,315	1,583
Four years prior to current fiscal year	1,327	318
Prior	2,682	2,560
Revolving line of credit arrangements	20,926	19,468
Loans, net of unearned income	60,279	57,524
Corporate loans | Non-investment grade, accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,811	4,103
One year prior to current fiscal year	2,292	529
Two years prior to current fiscal year	353	255
Three years prior to current fiscal year	211	655
Four years prior to current fiscal year	601	41
Prior	328	355
Revolving line of credit arrangements	3,861	2,489
Loans, net of unearned income	9,457	8,427
Corporate loans | Non-investment grade, accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	247	801
One year prior to current fiscal year	664	1,112
Two years prior to current fiscal year	1,378	1,936
Three years prior to current fiscal year	1,784	1,400
Four years prior to current fiscal year	1,146	770
Prior	1,730	1,190
Revolving line of credit arrangements	503	472
Loans, net of unearned income	7,452	7,681
Corporate loans | Non-investment grade, accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,879	1,227
One year prior to current fiscal year	826	592
Two years prior to current fiscal year	602	427
Three years prior to current fiscal year	210	261
Four years prior to current fiscal year	152	190
Prior	386	274
Revolving line of credit arrangements	1,625	2,304
Loans, net of unearned income	5,680	5,275
Corporate loans | Non-investment grade, non-accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	14	43
One year prior to current fiscal year	82	78
Two years prior to current fiscal year	87	48
Three years prior to current fiscal year	56	17
Four years prior to current fiscal year	48	7
Prior	33	44
Revolving line of credit arrangements	291	305
Loans, net of unearned income	611	542
Corporate loans | Non-investment grade, non-accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	8	0
One year prior to current fiscal year	0	0
Two years prior to current fiscal year	0	0
Three years prior to current fiscal year	0	55
Four years prior to current fiscal year	49	0
Prior	0	0
Revolving line of credit arrangements	17	18
Loans, net of unearned income	74	73
Corporate loans | Non-investment grade, non-accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2	16
One year prior to current fiscal year	0	2
Two years prior to current fiscal year	2	104
Three years prior to current fiscal year	8	107
Four years prior to current fiscal year	211	28
Prior	350	279
Revolving line of credit arrangements	36	31
Loans, net of unearned income	609	567
Corporate loans | Non-investment grade, non-accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
One year prior to current fiscal year	6	0
Two years prior to current fiscal year	34	1
Three years prior to current fiscal year	0	18
Four years prior to current fiscal year	14	0
Prior	22	19
Revolving line of credit arrangements	6	156
Loans, net of unearned income	$ 82	$ 195