LOANS AND LEASES - Origination Year (Details) $ in Millions	Jun. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 5,251
2019	5,086
2018	3,595
2017	2,811
2016	2,079
Prior	4,644
Revolving Loans Amortized Cost Basis	2,696
Total Loans and Leases	26,162
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	762
2019	1,861
2018	1,375
2017	1,307
2016	1,159
Prior	2,641
Revolving Loans Amortized Cost Basis	200
Total Loans and Leases	9,305
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	760
2019	1,848
2018	1,320
2017	1,209
2016	1,056
Prior	2,350
Revolving Loans Amortized Cost Basis	192
Total Loans and Leases	8,735
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2
2019	10
2018	43
2017	51
2016	44
Prior	159
Revolving Loans Amortized Cost Basis	3
Total Loans and Leases	312
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	3
2018	12
2017	47
2016	59
Prior	132
Revolving Loans Amortized Cost Basis	5
Total Loans and Leases	258
Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,255
2019	1,207
2018	812
2017	504
2016	184
Prior	487
Revolving Loans Amortized Cost Basis	1,260
Total Loans and Leases	7,709
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,249
2019	1,169
2018	727
2017	453
2016	162
Prior	420
Revolving Loans Amortized Cost Basis	1,113
Total Loans and Leases	7,293
Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5
2019	20
2018	59
2017	31
2016	16
Prior	31
Revolving Loans Amortized Cost Basis	61
Total Loans and Leases	223
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	18
2018	26
2017	20
2016	6
Prior	36
Revolving Loans Amortized Cost Basis	86
Total Loans and Leases	193
Commercial Leases [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	132
2019	162
2018	111
2017	72
2016	12
Prior	8
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	497
Commercial Leases [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	122
2019	159
2018	105
2017	67
2016	9
Prior	6
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	468
Commercial Leases [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9
2019	1
2018	4
2017	4
2016	2
Prior	2
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	22
Commercial Leases [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	2
2018	2
2017	1
2016	1
Prior	0
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	7
Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	4
Revolving Loans Amortized Cost Basis	36
Total Loans and Leases	40
Other [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	3
Revolving Loans Amortized Cost Basis	36
Total Loans and Leases	39
Other [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	1
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1
Total Commercial Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,149
2019	3,230
2018	2,298
2017	1,883
2016	1,355
Prior	3,140
Revolving Loans Amortized Cost Basis	1,496
Total Loans and Leases	17,551
Direct Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	355
2019	406
2018	252
2017	178
2016	208
Prior	548
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,947
Direct Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	355
2019	406
2018	251
2017	177
2016	206
Prior	534
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,929
Direct Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	1
2017	1
2016	2
Prior	14
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	18
Residential Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	544
2019	867
2018	435
2017	501
2016	405
Prior	767
Revolving Loans Amortized Cost Basis	1
Total Loans and Leases	3,520
Residential Mortgages [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	544
2019	864
2018	433
2017	498
2016	402
Prior	748
Revolving Loans Amortized Cost Basis	1
Total Loans and Leases	3,490
Residential Mortgages [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	3
2018	2
2017	3
2016	3
Prior	19
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	30
Indirect Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	200
2019	574
2018	598
2017	244
2016	105
Prior	46
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,767
Indirect Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	199
2019	571
2018	595
2017	242
2016	104
Prior	45
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,756
Indirect Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	3
2018	3
2017	2
2016	1
Prior	1
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	11
Consumer Lines of Credit [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3
2019	9
2018	12
2017	5
2016	6
Prior	143
Revolving Loans Amortized Cost Basis	1,199
Total Loans and Leases	1,377
Consumer Lines of Credit [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3
2019	9
2018	12
2017	5
2016	6
Prior	131
Revolving Loans Amortized Cost Basis	1,198
Total Loans and Leases	1,364
Consumer Lines of Credit [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	12
Revolving Loans Amortized Cost Basis	1
Total Loans and Leases	13
Consumer Loan [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,102
2019	1,856
2018	1,297
2017	928
2016	724
Prior	1,504
Revolving Loans Amortized Cost Basis	1,200
Total Loans and Leases	$ 8,611