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Mortgage Servicing Rights (Economic Assumptions) (Details) - USD ($) | 9 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020
Servicing Asset Key Economic Assumptions [Line Items] |  |
Weighted average constant prepayment rate | 17.32% | 20.62%
Weighted average cost to service a loan | $ 87.58 | $ 87.58
Fixed Rate Residential Mortgage |  |
Servicing Asset Key Economic Assumptions [Line Items] |  |
Discount rate | 8.49% | 7.92%
Discount rate, basis spread on Treasury rate | 700.00% |
All Loans and Leases, Excluding Conventional Fixed Loans |  |
Servicing Asset Key Economic Assumptions [Line Items] |  |
Discount rate | 9.49% | 8.92%
Discount rate, basis spread on Treasury rate | 800.00% |

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- Definition [Line Items] for The key economic assumptions used to value servicing assets. + References No definition available. + Details
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- Definition Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Cost to Service Loans, Per Loan + References No definition available. + Details
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- Definition Discount rate used to estimate the fair value of servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746 + Details
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- Definition Estimated rate of prepayments of principal on servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122596-111746 + Details
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