LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 733,905	$ 694,488
Loans at fair value	7,896	8,040
Unallocated portfolio layer cumulative basis adjustments		(72)
Corporate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	103,028	91,339
One year prior to current fiscal year	33,849	24,201
Two years prior to current fiscal year	21,575	19,849
Three years prior to current fiscal year	15,196	10,274
Four years prior to current fiscal year	7,387	5,460
Prior	16,019	18,185
Revolving line of credit arrangements	130,300	124,391
Loans, net of unearned income	335,277	301,386
Loans at fair value	7,870	7,759
Loans net of unearned income, before adjustments	335,224	301,458
Unallocated portfolio layer cumulative basis adjustments	53	(72)
Corporate loans | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	72,444	60,211
One year prior to current fiscal year	25,049	16,807
Two years prior to current fiscal year	14,620	13,502
Three years prior to current fiscal year	10,826	6,177
Four years prior to current fiscal year	4,632	4,106
Prior	10,787	13,464
Revolving line of credit arrangements	101,733	99,148
Loans, net of unearned income	240,091	213,415
Corporate loans | Investment grade | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	36,056	36,039
One year prior to current fiscal year	10,143	8,101
Two years prior to current fiscal year	6,083	5,035
Three years prior to current fiscal year	4,389	2,492
Four years prior to current fiscal year	1,780	1,225
Prior	4,292	4,853
Revolving line of credit arrangements	29,446	32,862
Loans, net of unearned income	92,189	90,607
Corporate loans | Investment grade | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20,658	13,074
One year prior to current fiscal year	5,912	2,136
Two years prior to current fiscal year	2,311	1,162
Three years prior to current fiscal year	1,375	326
Four years prior to current fiscal year	546	265
Prior	2,074	1,500
Revolving line of credit arrangements	46,114	41,415
Loans, net of unearned income	78,990	59,878
Corporate loans | Investment grade | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,760	5,325
One year prior to current fiscal year	4,942	3,927
Two years prior to current fiscal year	3,635	3,269
Three years prior to current fiscal year	2,431	2,537
Four years prior to current fiscal year	1,678	1,460
Prior	1,960	1,533
Revolving line of credit arrangements	418	248
Loans, net of unearned income	18,824	18,299
Corporate loans | Investment grade | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	11,970	5,773
One year prior to current fiscal year	4,052	2,643
Two years prior to current fiscal year	2,591	4,036
Three years prior to current fiscal year	2,631	822
Four years prior to current fiscal year	628	1,156
Prior	2,461	5,578
Revolving line of credit arrangements	25,755	24,623
Loans, net of unearned income	50,088	44,631
Corporate loans | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	30,584	31,128
One year prior to current fiscal year	8,800	7,395
Two years prior to current fiscal year	6,955	6,347
Three years prior to current fiscal year	4,370	4,096
Four years prior to current fiscal year	2,755	1,354
Prior	5,232	4,721
Revolving line of credit arrangements	28,567	25,243
Loans, net of unearned income	87,263	80,284
Corporate loans | Non-investment grade, accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	24,142	24,937
One year prior to current fiscal year	5,546	5,082
Two years prior to current fiscal year	3,925	3,576
Three years prior to current fiscal year	2,418	1,583
Four years prior to current fiscal year	762	318
Prior	2,573	2,560
Revolving line of credit arrangements	20,656	19,468
Loans, net of unearned income	60,022	57,524
Corporate loans | Non-investment grade, accrual | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	3,475	4,103
One year prior to current fiscal year	1,377	529
Two years prior to current fiscal year	791	255
Three years prior to current fiscal year	130	655
Four years prior to current fiscal year	432	41
Prior	205	355
Revolving line of credit arrangements	4,663	2,489
Loans, net of unearned income	11,073	8,427
Corporate loans | Non-investment grade, accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	760	801
One year prior to current fiscal year	901	1,112
Two years prior to current fiscal year	1,482	1,936
Three years prior to current fiscal year	1,317	1,400
Four years prior to current fiscal year	1,091	770
Prior	1,681	1,190
Revolving line of credit arrangements	571	472
Loans, net of unearned income	7,803	7,681
Corporate loans | Non-investment grade, accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,051	1,227
One year prior to current fiscal year	916	592
Two years prior to current fiscal year	593	427
Three years prior to current fiscal year	214	261
Four years prior to current fiscal year	115	190
Prior	381	274
Revolving line of credit arrangements	2,024	2,304
Loans, net of unearned income	6,294	5,275
Corporate loans | Non-investment grade, non-accrual | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	72	43
One year prior to current fiscal year	35	78
Two years prior to current fiscal year	98	48
Three years prior to current fiscal year	54	17
Four years prior to current fiscal year	44	7
Prior	59	44
Revolving line of credit arrangements	541	305
Loans, net of unearned income	903	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	45	0
Prior	0	0
Revolving line of credit arrangements	24	18
Loans, net of unearned income	77	73
Corporate loans | Non-investment grade, non-accrual | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	33	16
One year prior to current fiscal year	10	2
Two years prior to current fiscal year	46	104
Three years prior to current fiscal year	237	107
Four years prior to current fiscal year	203	28
Prior	328	279
Revolving line of credit arrangements	67	31
Loans, net of unearned income	924	567
Corporate loans | Non-investment grade, non-accrual | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	43	1
One year prior to current fiscal year	15	0
Two years prior to current fiscal year	20	1
Three years prior to current fiscal year	0	18
Four years prior to current fiscal year	63	0
Prior	5	19
Revolving line of credit arrangements	21	156
Loans, net of unearned income	$ 167	$ 195