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12) Mortgage Servicing Rights: Assumptions used in determining MSR value (Details) - Decimal | 3 Months Ended | 12 Months Ended
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Mar. 31, 2021 | Dec. 31, 2020
Text Block [Abstract] |  |
Prepayment Speeds | 11.90 | 15.60
Average Life in Years of MSR | 6 years 8 months 19 days | 5 years 3 months 19 days
Discount Rate | 9.50 | 9.50

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