LOANS AND LEASES - Origination Year (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 1,590	$ 6,587
Fiscal year before current fiscal year	6,752	4,518
Two years before current fiscal year	4,499	3,256
Three years before current fiscal year	3,156	1,952
Four years before current fiscal year	1,901	1,579
Prior	5,913	4,130
Revolving Loans Amortized Cost Basis	3,028	2,946
Total Loans and Leases	26,839	24,968
Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	26,661	24,815
Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	178	153
Total commercial loans and leases
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	929	3,786
Fiscal year before current fiscal year	3,792	2,779
Two years before current fiscal year	2,803	2,484
Three years before current fiscal year	2,395	1,486
Four years before current fiscal year	1,478	1,200
Prior	4,233	2,858
Revolving Loans Amortized Cost Basis	1,951	1,872
Total Loans and Leases	17,581	16,465
Total commercial loans and leases | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	17,490	16,385
Total commercial loans and leases | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	91	80
Total commercial loans and leases | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	423	1,893
Fiscal year before current fiscal year	2,167	1,818
Two years before current fiscal year	1,853	1,620
Three years before current fiscal year	1,616	980
Four years before current fiscal year	994	895
Prior	3,487	2,498
Revolving Loans Amortized Cost Basis	206	195
Total Loans and Leases	10,746	9,899
Total commercial loans and leases | Commercial real estate | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	10,677	9,840
Total commercial loans and leases | Commercial real estate | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	69	59
Total commercial loans and leases | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	423	1,878
Fiscal year before current fiscal year	2,123	1,782
Two years before current fiscal year	1,813	1,503
Three years before current fiscal year	1,480	830
Four years before current fiscal year	839	743
Prior	2,937	2,171
Revolving Loans Amortized Cost Basis	196	183
Total Loans and Leases	9,811	9,090
Total commercial loans and leases | Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	15
Fiscal year before current fiscal year	44	21
Two years before current fiscal year	24	89
Three years before current fiscal year	93	105
Four years before current fiscal year	101	107
Prior	306	175
Revolving Loans Amortized Cost Basis	1	9
Total Loans and Leases	569	521
Total commercial loans and leases | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	15
Two years before current fiscal year	16	28
Three years before current fiscal year	43	45
Four years before current fiscal year	54	45
Prior	244	152
Revolving Loans Amortized Cost Basis	9	3
Total Loans and Leases	366	288
Total commercial loans and leases | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	427	1,672
Fiscal year before current fiscal year	1,459	849
Two years before current fiscal year	850	763
Three years before current fiscal year	729	450
Four years before current fiscal year	444	263
Prior	638	355
Revolving Loans Amortized Cost Basis	1,673	1,625
Total Loans and Leases	6,220	5,977
Total commercial loans and leases | Commercial and industrial | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	6,202	5,958
Total commercial loans and leases | Commercial and industrial | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	18	19
Total commercial loans and leases | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	426	1,663
Fiscal year before current fiscal year	1,444	833
Two years before current fiscal year	823	731
Three years before current fiscal year	697	386
Four years before current fiscal year	390	184
Prior	475	296
Revolving Loans Amortized Cost Basis	1,576	1,509
Total Loans and Leases	5,831	5,602
Total commercial loans and leases | Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	8
Fiscal year before current fiscal year	7	12
Two years before current fiscal year	16	18
Three years before current fiscal year	18	7
Four years before current fiscal year	28	37
Prior	101	42
Revolving Loans Amortized Cost Basis	32	52
Total Loans and Leases	203	176
Total commercial loans and leases | Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
Fiscal year before current fiscal year	8	4
Two years before current fiscal year	11	14
Three years before current fiscal year	14	57
Four years before current fiscal year	26	42
Prior	62	17
Revolving Loans Amortized Cost Basis	65	64
Total Loans and Leases	186	199
Total commercial loans and leases | Commercial leases
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	22	182
Fiscal year before current fiscal year	166	112
Two years before current fiscal year	100	101
Three years before current fiscal year	50	56
Four years before current fiscal year	40	42
Prior	93	2
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	471	495
Total commercial loans and leases | Commercial leases | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	470	493
Total commercial loans and leases | Commercial leases | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	1	2
Total commercial loans and leases | Commercial leases | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	22	182
Fiscal year before current fiscal year	165	109
Two years before current fiscal year	98	98
Three years before current fiscal year	48	53
Four years before current fiscal year	40	39
Prior	90	1
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	463	482
Total commercial loans and leases | Commercial leases | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	1	1
Two years before current fiscal year	0	0
Three years before current fiscal year	0	2
Four years before current fiscal year	0	3
Prior	0	1
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	1	7
Total commercial loans and leases | Commercial leases | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	2
Two years before current fiscal year	2	3
Three years before current fiscal year	2	1
Four years before current fiscal year	0	0
Prior	3	0
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	7	6
Total commercial loans and leases | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	57	39
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	15	3
Revolving Loans Amortized Cost Basis	72	52
Total Loans and Leases	144	94
Total commercial loans and leases | Other | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	141	94
Total commercial loans and leases | Other | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	3	0
Total commercial loans and leases | Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	57	39
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	15	3
Revolving Loans Amortized Cost Basis	72	52
Total Loans and Leases	144	94
Total consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	661	2,801
Fiscal year before current fiscal year	2,960	1,739
Two years before current fiscal year	1,696	772
Three years before current fiscal year	761	466
Four years before current fiscal year	423	379
Prior	1,680	1,272
Revolving Loans Amortized Cost Basis	1,077	1,074
Total Loans and Leases	9,258	8,503
Total consumer loans | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	9,171	8,430
Total consumer loans | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans and Leases	87	73
Total consumer loans | Direct installment
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	265	978
Fiscal year before current fiscal year	983	538
Two years before current fiscal year	524	216
Three years before current fiscal year	198	126
Four years before current fiscal year	113	96
Prior	485	422
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	2,568	2,376
Total consumer loans | Direct installment | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	265	978
Fiscal year before current fiscal year	983	538
Two years before current fiscal year	523	215
Three years before current fiscal year	197	125
Four years before current fiscal year	112	96
Prior	475	412
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	2,555	2,364
Total consumer loans | Direct installment | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	1	1
Three years before current fiscal year	1	1
Four years before current fiscal year	1	0
Prior	10	10
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	13	12
Total consumer loans | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	237	1,281
Fiscal year before current fiscal year	1,474	933
Two years before current fiscal year	933	393
Three years before current fiscal year	420	155
Four years before current fiscal year	155	215
Prior	969	677
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	4,188	3,654
Total consumer loans | Residential mortgages | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	237	1,280
Fiscal year before current fiscal year	1,470	932
Two years before current fiscal year	929	392
Three years before current fiscal year	418	152
Four years before current fiscal year	152	212
Prior	935	652
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	4,141	3,620
Total consumer loans | Residential mortgages | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
Fiscal year before current fiscal year	4	1
Two years before current fiscal year	4	1
Three years before current fiscal year	2	3
Four years before current fiscal year	3	3
Prior	34	25
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	47	34
Total consumer loans | Indirect installment
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	127	522
Fiscal year before current fiscal year	483	265
Two years before current fiscal year	237	159
Three years before current fiscal year	139	180
Four years before current fiscal year	150	65
Prior	80	36
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	1,216	1,227
Total consumer loans | Indirect installment | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	127	516
Fiscal year before current fiscal year	478	262
Two years before current fiscal year	235	157
Three years before current fiscal year	137	178
Four years before current fiscal year	149	64
Prior	78	35
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	1,204	1,212
Total consumer loans | Indirect installment | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	6
Fiscal year before current fiscal year	5	3
Two years before current fiscal year	2	2
Three years before current fiscal year	2	2
Four years before current fiscal year	1	1
Prior	2	1
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	12	15
Total consumer loans | Consumer lines of credit
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	32	20
Fiscal year before current fiscal year	20	3
Two years before current fiscal year	2	4
Three years before current fiscal year	4	5
Four years before current fiscal year	5	3
Prior	146	137
Revolving Loans Amortized Cost Basis	1,077	1,074
Total Loans and Leases	1,286	1,246
Total consumer loans | Consumer lines of credit | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	32	20
Fiscal year before current fiscal year	20	3
Two years before current fiscal year	2	4
Three years before current fiscal year	4	5
Four years before current fiscal year	5	3
Prior	133	127
Revolving Loans Amortized Cost Basis	1,075	1,072
Total Loans and Leases	1,271	1,234
Total consumer loans | Consumer lines of credit | Past due
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	13	10
Revolving Loans Amortized Cost Basis	2	2
Total Loans and Leases	$ 15	$ 12