INVESTMENT SECURITIES (Schedule of Securities with Unrealized Losses) (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($) item
Marketable equity securities
Number of securities of one issuer \| item	0	0
Impairment loss	$ 0	$ 0
Equity securities
Marketable equity securities
Less than 12 Months, Estimated Fair Value	2,281
Less than 12 Months, Unrealized/Unrecognized Losses	(27)
Total, Estimated Fair Value	2,281
Total, Unrealized Losses	(27)
Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	325,695	83,964
Less than 12 Months, Unrealized/Unrecognized Losses	(5,954)	(248)
12 months or more, Estimated Fair Value	383	385
12 months or more, Unrealized/Unrecognized Losses	(1)	(1)
Total, Estimated Fair Value	326,078	84,349
Total, Unrealized/Unrecognized Losses	(5,955)	(249)
Residential mortgage-backed securities \| Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	233,408	33,734
Less than 12 Months, Unrealized/Unrecognized Losses	(3,546)	(74)
Total, Estimated Fair Value	233,408	33,734
Total, Unrealized/Unrecognized Losses	(3,546)	(74)
Commercial mortgage-backed securities \| Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	9,520	12,314
Less than 12 Months, Unrealized/Unrecognized Losses	(270)	(93)
12 months or more, Estimated Fair Value	383	385
12 months or more, Unrealized/Unrecognized Losses	(1)	(1)
Total, Estimated Fair Value	9,903	12,699
Total, Unrealized/Unrecognized Losses	(271)	(94)
Asset-backed Securities \| Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	4,974
Less than 12 Months, Unrealized/Unrecognized Losses	(29)
Total, Estimated Fair Value	4,974
Total, Unrealized/Unrecognized Losses	(29)
U.S. Government agency securities \| Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	66,423	37,916
Less than 12 Months, Unrealized/Unrecognized Losses	(1,570)	(81)
Total, Estimated Fair Value	66,423	37,916
Total, Unrealized/Unrecognized Losses	(1,570)	$ (81)
Securities issued by states and political subdivisions in the U.S \| Available-for-sale Securities
Available-for-sale Securities
Less than 12 Months, Estimated Fair Value	11,370
Less than 12 Months, Unrealized/Unrecognized Losses	(539)
Total, Estimated Fair Value	11,370
Total, Unrealized/Unrecognized Losses	(539)
CRA mutual fund \| Equity securities
Marketable equity securities
Less than 12 Months, Estimated Fair Value	2,281
Less than 12 Months, Unrealized/Unrecognized Losses	(27)
Total, Estimated Fair Value	2,281
Total, Unrealized Losses	$ (27)

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