SECURITIES - Held to Maturity Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Amortized Cost, Held to maturity:
Within one year	$ 1,670
One to five years	28,305
Five to ten years	14,216
Beyond ten years	56,743
Total	100,934	$ 133,638
Estimated Fair Value, Held to maturity:
Within one year	1,676
One to five years	29,522
Five to ten years	15,081
Beyond ten years	58,632
Estimated Fair Value	104,911	135,027
State and municipal obligations
Amortized Cost, Held to maturity:
Total	26,886	41,008
Estimated Fair Value, Held to maturity:
Estimated Fair Value	28,374	41,817
U.S. GSE residential mortgage-backed securities
Amortized Cost, Held to maturity:
Total	6,822	8,142
Estimated Fair Value, Held to maturity:
Estimated Fair Value	7,051	8,093
U.S. GSE residential collateralized mortgage obligations
Amortized Cost, Held to maturity:
Total	25,413	39,936
Estimated Fair Value, Held to maturity:
Estimated Fair Value	26,084	40,498
U.S. GSE commercial mortgage-backed securities
Amortized Cost, Held to maturity:
Total	16,742	17,215
Estimated Fair Value, Held to maturity:
Estimated Fair Value	17,437	17,235
U.S. GSE commercial collateralized mortgage obligations
Amortized Cost, Held to maturity:
Total	25,071	27,337
Estimated Fair Value, Held to maturity:
Estimated Fair Value	$ 25,965	$ 27,384

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 320
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-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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