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SECURITIES (Narrative) (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 USD ($) | Dec. 31, 2019 USD ($) security | Dec. 31, 2018 USD ($) security
Schedule of Investments [Line Items] |  |  |
Available for sale securities that had been in a continuous loss position for more than 12 months |  | $ 75,000,000.0 | $ 385,400,000
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss |  | $ 696,000 | $ 10,184,000
Federal Home Loan Bank requires Bank to maintain percentage of stock equal to outstanding borrowings |  | 4.25% | 4.25%
Percentage of Federal Reserve Bank of Richmond reserve |  | 6.00% | 6.00%
Restricted equity securities consist of Federal Reserve Bank stock |  | $ 67,000,000.0 | $ 52,600,000
Federal Home Loan Bank Stock |  | 63,900,000 | 72,000,000.0
Credit-related OTTI |  | $ 0 | $ 0
Available-for-sale Securities |  |  |
Schedule of Investments [Line Items] |  |  |
Available for sale securities that had been in a continuous loss position | security |  | 47 | 138
Accounting Standards Update 2017-12 |  |  |
Schedule of Investments [Line Items] |  |  |
Available for sale debt securities, transfer, amount | $ 187,400,000 |  |

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- Definition Debt Securities, Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions. + References No definition available. + Details
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- Definition Federal home loan bank requires bank to maintain percentage of stock equal to outstanding borrowings. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 + Details
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- Definition Amount of investment in debt security, measured at amortized cost, transferred to investment in debt security, measured at fair value, with change in fair value recognized in other comprehensive income (available-for-sale) and net income (trading). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27405-111563 + Details
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- Definition Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 325 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=75031641&loc=d3e63345-112809 + Details
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