LOANS AND ALLOWANCE FOR CREDIT LOSSES ON LOANS (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Activity in ALL:
Beginning balance	$ 37,865	$ 25,171	$ 25,171
Loans charged off	(287)	(490)	(1,838)
Recoveries	51	68	1,084
Provision	(1,854)	1,772	13,215
Ending balance	35,775	26,521	37,865
Ending Balance: Individually evaluated for impairment		447
Ending Balance: Collectively evaluated for impairment		26,074
Ending Balance: Individually evaluated for impairment		4,355
Ending Balance: Collectively evaluated for impairment		3,153,407
Total Loans Outstanding	3,237,046	3,157,762	3,219,822
Commercial Real Estate(1)
Activity in ALL:
Beginning balance		12,414	12,414
Loans charged off		(50)
Recoveries		4
Provision		1,006
Ending balance		13,374
Ending Balance: Individually evaluated for impairment		34
Ending Balance: Collectively evaluated for impairment		13,340
Ending Balance: Individually evaluated for impairment		400
Ending Balance: Collectively evaluated for impairment		1,299,460
Total Loans Outstanding		1,299,860
Commercial
Activity in ALL:
Beginning balance	6,703	3,985	3,985
Loans charged off	(147)	(253)	(1,130)
Recoveries	43	53	572
Provision	(1,429)	512	1,728
Ending balance	5,170	4,297	6,703
Ending Balance: Individually evaluated for impairment		0
Ending Balance: Collectively evaluated for impairment		4,297
Ending Balance: Individually evaluated for impairment		299
Ending Balance: Collectively evaluated for impairment		462,788
Total Loans Outstanding	366,159	463,087	381,494
SBA PPP Portfolio Segment
Activity in ALL:
Beginning balance	69	0	0
Loans charged off	0		0
Recoveries	0		0
Provision	18		69
Ending balance	87		69
Total Loans Outstanding	169,407		135,095
Residential Real Estate
Activity in ALL:
Beginning balance	3,474	5,842	5,842
Loans charged off	(53)	(96)	(121)
Recoveries	0	2	292
Provision	(328)	149	(1,410)
Ending balance	3,093	5,897	3,474
Ending Balance: Individually evaluated for impairment		324
Ending Balance: Collectively evaluated for impairment		5,573
Ending Balance: Individually evaluated for impairment		3,286
Ending Balance: Collectively evaluated for impairment		1,060,926
Total Loans Outstanding	1,051,765	1,064,212	1,054,798
Home Equity
Activity in ALL:
Beginning balance	2,616	2,423	2,423
Loans charged off	(38)	(34)	(317)
Recoveries	0	4	33
Provision	(402)	87	(315)
Ending balance	2,176	2,480	2,616
Ending Balance: Individually evaluated for impairment		89
Ending Balance: Collectively evaluated for impairment		2,391
Ending Balance: Individually evaluated for impairment		370
Ending Balance: Collectively evaluated for impairment		305,856
Total Loans Outstanding	240,486	306,226	258,573
Consumer
Activity in ALL:
Beginning balance	393	507	507
Loans charged off	(49)	(57)	(167)
Recoveries	6	5	67
Provision	(122)	18	206
Ending balance	228	473	393
Ending Balance: Individually evaluated for impairment		0
Ending Balance: Collectively evaluated for impairment		473
Ending Balance: Individually evaluated for impairment		0
Ending Balance: Collectively evaluated for impairment		24,377
Total Loans Outstanding	$ 18,902	$ 24,377	$ 20,392

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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