LOANS AND LEASES - Origination Year (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 6,501
2019	4,659
2018	3,086
2017	2,533
2016	1,948
Prior	4,411
Revolving Loans Amortized Cost Basis	2,551
Total Loans and Leases	25,689	$ 23,289
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,354
2019	1,866
2018	1,284
2017	1,247
2016	1,129
Prior	2,489
Revolving Loans Amortized Cost Basis	152
Total Loans and Leases	9,521
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,343
2019	1,810
2018	1,194
2017	1,086
2016	936
Prior	2,071
Revolving Loans Amortized Cost Basis	144
Total Loans and Leases	8,584
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	10
2019	31
2018	58
2017	74
2016	60
Prior	166
Revolving Loans Amortized Cost Basis	3
Total Loans and Leases	402
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	25
2018	32
2017	87
2016	133
Prior	252
Revolving Loans Amortized Cost Basis	5
Total Loans and Leases	535
Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,364
2019	1,149
2018	750
2017	441
2016	157
Prior	496
Revolving Loans Amortized Cost Basis	1,190
Total Loans and Leases	7,547	5,308
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,355
2019	1,092
2018	655
2017	363
2016	138
Prior	422
Revolving Loans Amortized Cost Basis	1,052
Total Loans and Leases	7,077
Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5
2019	26
2018	40
2017	38
2016	12
Prior	28
Revolving Loans Amortized Cost Basis	59
Total Loans and Leases	208
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4
2019	31
2018	55
2017	40
2016	7
Prior	46
Revolving Loans Amortized Cost Basis	79
Total Loans and Leases	262
Commercial Leases [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	122
2019	183
2018	101
2017	66
2016	9
Prior	6
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	487	432
Commercial Leases [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	114
2019	179
2018	94
2017	61
2016	7
Prior	4
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	459
Commercial Leases [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1
2018	5
2017	4
2016	1
Prior	2
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	13
Commercial Leases [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8
2019	3
2018	2
2017	1
2016	1
Prior	0
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	15
Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	21
2019	0
2018	0
2017	0
2016	0
Prior	4
Revolving Loans Amortized Cost Basis	40
Total Loans and Leases	65	21
Other [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	21
2019	0
2018	0
2017	0
2016	0
Prior	3
Revolving Loans Amortized Cost Basis	40
Total Loans and Leases	64
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	4,861
2019	3,198
2018	2,135
2017	1,754
2016	1,295
Prior	2,995
Revolving Loans Amortized Cost Basis	1,382
Total Loans and Leases	17,620	14,721
Direct Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	525
2019	371
2018	227
2017	161
2016	190
Prior	503
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,977	1,821
Direct Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	525
2019	370
2018	226
2017	160
2016	188
Prior	489
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,958
Direct Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1
2018	1
2017	1
2016	2
Prior	14
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	19
Residential Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	863
2019	808
2018	349
2017	443
2016	373
Prior	693
Revolving Loans Amortized Cost Basis	2
Total Loans and Leases	3,531	3,374
Residential Mortgages [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	862
2019	803
2018	344
2017	437
2016	367
Prior	661
Revolving Loans Amortized Cost Basis	2
Total Loans and Leases	3,476
Residential Mortgages [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	5
2018	5
2017	6
2016	6
Prior	32
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	55
Indirect Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	249
2019	274
2018	366
2017	171
2016	84
Prior	75
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,219	1,922
Indirect Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	249
2019	273
2018	364
2017	169
2016	83
Prior	69
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	1,207
Indirect Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1
2018	2
2017	2
2016	1
Prior	6
Revolving Loans Amortized Cost Basis	0
Total Loans and Leases	12
Consumer Lines of Credit [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3
2019	8
2018	9
2017	4
2016	6
Prior	145
Revolving Loans Amortized Cost Basis	1,167
Total Loans and Leases	1,342	1,451
Consumer Lines of Credit [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3
2019	8
2018	9
2017	4
2016	5
Prior	133
Revolving Loans Amortized Cost Basis	1,166
Total Loans and Leases	1,328
Consumer Lines of Credit [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	1
Prior	12
Revolving Loans Amortized Cost Basis	1
Total Loans and Leases	14
Consumer Loan [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,640
2019	1,461
2018	951
2017	779
2016	653
Prior	1,416
Revolving Loans Amortized Cost Basis	1,169
Total Loans and Leases	$ 8,069	$ 8,568