SECURITIES - Summary of Held to Maturity Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Held to maturity:
Amortized Cost	$ 85,700	$ 133,638
Gross Unrealized Gains	3,634	1,731
Gross Unrealized Losses	(9)	(342)
Estimated Fair Value	89,325	135,027
State and municipal obligations
Held to maturity:
Amortized Cost	23,715	41,008
Gross Unrealized Gains	1,406	809
Estimated Fair Value	25,121	41,817
U.S. GSE residential mortgage-backed securities
Held to maturity:
Amortized Cost	6,272	8,142
Gross Unrealized Gains	227	5
Gross Unrealized Losses		(54)
Estimated Fair Value	6,499	8,093
U.S. GSE residential collateralized mortgage obligations
Held to maturity:
Amortized Cost	18,511	39,936
Gross Unrealized Gains	489	624
Gross Unrealized Losses	(9)	(62)
Estimated Fair Value	18,991	40,498
U.S. GSE commercial mortgage-backed securities
Held to maturity:
Amortized Cost	13,069	17,215
Gross Unrealized Gains	625	102
Gross Unrealized Losses		(82)
Estimated Fair Value	13,694	17,235
U.S. GSE commercial collateralized mortgage obligations
Held to maturity:
Amortized Cost	24,133	27,337
Gross Unrealized Gains	887	191
Gross Unrealized Losses		(144)
Estimated Fair Value	$ 25,020	$ 27,384

Amount of investment in debt security measured at amortized cost (held-to-maturity).

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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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