LOANS AND LEASES - Restructured Loans (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) loans	Jun. 30, 2019 USD ($) loans	Jun. 30, 2020 USD ($) loans d	Jun. 30, 2019 USD ($) loans	Dec. 31, 2019 USD ($) loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			32	42
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 15,324,000	$ 26,681,000
Financing Receivable, Troubled Debt Restructuring, Postmodification			15,234,000	26,289,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default			$ 0	6,800,000
Number of Restructured Loans | loans	175		175		157
Total restructured loans	$ 41,000,000.0		$ 41,000,000.0		$ 30,000,000.0
Document Period End Date			Jun. 30, 2020
Restructured loans on accrual status	8,400,000		$ 8,400,000		11,400,000
Restructured Loans, Nonaccrual Status	32,700,000		32,700,000		18,500,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	200,000		200,000		2,500,000
Allowance for loan and lease losses lncluded in reserves for restructured loans	4,800,000		4,800,000		2,500,000
Restructured Loans, Portion Determined to be Uncollectible	700,000	$ 0	1,100,000	$ 0
Accruing TDRs performing in accordance with restructured terms for more than one year	$ 5,200,000		$ 5,200,000		$ 4,700,000
Restructured loans performance threshold (days) | d			90
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | loans			0	2
Financing Receivable Modifications, Contracts, Number | loans	11	25
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 2,600,000	$ 17,245,000
Financing Receivable Modifications, Post Modification Investment Recorded	$ 2,577,000	$ 16,921,000
Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			7	6
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 13,504,000	$ 22,527,000
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 13,504,000	$ 22,550,000
Financing Receivable Modifications, Contracts, Number | loans	5	1
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 2,121,000	$ 14,889,000
Financing Receivable Modifications, Post Modification Investment Recorded	$ 2,121,000	$ 14,889,000
Construction real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			0	0
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 0	$ 0
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 0	$ 0
Financing Receivable Modifications, Contracts, Number | loans	0	0
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 0	$ 0
Financing Receivable Modifications, Post Modification Investment Recorded	$ 0	$ 0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			0	7
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 0	$ 1,365,000
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 0	$ 1,274,000
Financing Receivable Modifications, Contracts, Number | loans	0	1
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 0	$ 42,000
Financing Receivable Modifications, Post Modification Investment Recorded	$ 0	$ 42,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			18	17
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 1,568,000	$ 2,466,000
Financing Receivable, Troubled Debt Restructuring, Postmodification			1,489,000	$ 2,171,000
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			$ 250,000
Financing Receivable Modifications, Contracts, Number | loans	4	12
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 439,000	$ 2,008,000
Financing Receivable Modifications, Post Modification Investment Recorded	$ 416,000	$ 1,713,000
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			6	12
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 226,000	$ 323,000
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 226,000	$ 294,000
Financing Receivable Modifications, Contracts, Number | loans	2	11
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 40,000	$ 306,000
Financing Receivable Modifications, Post Modification Investment Recorded	$ 40,000	$ 277,000
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			1	0
Financing Receivable, Troubled Debt Restructuring, Premodification			$ 26,000	$ 0
Financing Receivable, Troubled Debt Restructuring, Postmodification			$ 15,000	$ 0
Financing Receivable Modifications, Contracts, Number | loans	0	0
Financing Receivable Modifications, Pre Modification Investment Recorded	$ 0	$ 0
Financing Receivable Modifications, Post Modification Investment Recorded	0	$ 0
Payment Deferral [Member] | Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			1,950
Total restructured loans	2,100,000,000		$ 2,100,000,000
Payment Deferral [Member] | Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans			1,151
Total restructured loans	$ 126,200,000		$ 126,200,000