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Loans and Allowance for Credit Losses on Loans - Major Classifications - Loan Concentrations (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2020 | Dec. 31, 2019 | Apr. 20, 2018
Loans |  |  |
Loans |  |  | $ 227.6
Real Estate Portfolio Segment [Member] | Loan receivables | Customer Concentration Risk [Member] |  |  |
Loans |  |  |
Credit risk as a percentage of benchmark |  | 75.40% |
Loans receivable as a percentage of total portfolio | 71.40% |  |

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