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LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2020 USD ($) | Jun. 30, 2020 USD ($) | Sep. 30, 2020 USD ($) contract | Sep. 30, 2019 contract | Dec. 31, 2019 USD ($) contract
Financing Receivable Allowance For Credit Losses [Line Items] |  |  |  |  |
Provision for Credit Loss, Expense (Reversal) | $ (300,000,000) |  |  |  |
Loans classified in doubtful or loss risk rating | $ 0 |  | $ 0 |  | $ 0
Number of loans modified as TDRs | contract |  |  | 1 | 4 | 4
Increase in allowance for loan losses due to TDRs |  |  |  |  | $ 0
Troubled debt restructuring charge-offs |  |  |  |  | $ 0
COVID-19 |  |  |  |  |
Financing Receivable Allowance For Credit Losses [Line Items] |  |  |  |  |
Provision for Credit Loss, Expense (Reversal) |  | $ 12,100,000 |  |  |

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- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524 + Details
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- Definition Amount of credit loss expense (reversal of expense) for financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(11)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
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