LOANS AND LEASES - Restructured Loans (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) loans	Sep. 30, 2019 USD ($) loans	Sep. 30, 2020 USD ($) loans d	Sep. 30, 2019 USD ($) loans	Dec. 31, 2019 USD ($) loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts	7	11	39	53
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 1,709,000	$ 4,684,000	$ 17,033,000	$ 31,365,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 1,690,000	4,699,000	$ 16,924,000	30,988,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		100,000		7,000,000.0
Number of Restructured Loans | loans	169		169		157
Total restructured loans	$ 37,100,000		$ 37,100,000		$ 30,000,000.0
Restructured loans on accrual status	7,800,000		7,800,000		11,400,000
Restructured Loans, Nonaccrual Status	29,300,000		29,300,000		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	5,700,000		5,700,000		2,500,000
Restructured Loans, Portion Determined to be Uncollectible	600,000	$ 2,300,000	1,700,000	$ 2,300,000
Accruing TDRs performing in accordance with restructured terms for more than one year	$ 5,400,000		$ 5,400,000		$ 4,700,000
Restructured loans performance threshold (days) | d			90
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | loans	1	1	1	3
Commercial segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	1	2	8	8
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 1,480,000	$ 2,482,000	$ 14,984,000	$ 25,009,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 1,480,000	$ 2,521,000	$ 14,984,000	$ 25,071,000
Construction real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	0	0	0
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 0	$ 0	$ 0	$ 0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	2	0	9
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 0	$ 1,659,000	$ 0	$ 3,024,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 0	$ 1,658,000	$ 0	$ 2,932,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	2	5	20	22
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 109,000	$ 478,000	$ 1,677,000	$ 2,944,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 92,000	$ 455,000	1,581,000	$ 2,626,000
Restructured Loans, Loan Relationships, Review Threshold Amount Minimum			$ 250,000
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	4	1	10	13
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 120,000	$ 35,000	$ 346,000	$ 358,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 118,000	$ 36,000	$ 344,000	$ 330,000
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1	1	1
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 0	$ 30,000	$ 26,000	$ 30,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 0	$ 29,000	$ 15,000	$ 29,000