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Mortgage Banking Activities, Mortgage Servicing Rights (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2020 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2019 USD ($)
Summary of Mortgage Servicing Rights [Abstract] |  |  |
Number of residential mortgage loans serviced for others | 124,819 |  | 126,828
Outstanding principal balance of residential mortgage loans serviced for others | $ 20,261,526,000 |  | $ 20,727,106,000
Weighted average interest rate | 3.96% |  | 3.98%
Remaining term (in months) | 287 months |  | 289 months
Servicing Asset at Fair Value, Amount [Roll Forward] |  |  |
Beginning balance | $ 201,886,000 | $ 259,254,000 | $ 259,254,000
Additions, net | 5,441,000 | 6,188,000 |
Change in fair value due to principal payments | (8,019,000) | (6,583,000) |
Change in fair value due to market assumption changes | (88,480,000) | (20,666,000) |
Ending balance | $ 110,828,000 | $ 238,193,000 | $ 201,886,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract] |  |  |
Discount rate - risk-free rate plus a market premium (in hundredths) | 9.80% |  | 9.81%
Prepayment rate - based upon loan interest rate, original term and loan type, minimum | 8.22% |  | 8.28%
Prepayment rate - based upon loan interest rate, original term and loan type, maximum | 32.80% |  | 16.05%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan) | $ 69 |  | $ 68
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan) | 94 |  | 94
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan) | 150 |  | 150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan) | 500 |  | 500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan) | 1,000 |  | 1,000
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan) | $ 4,000 |  | $ 4,000
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths) | 0.53% |  | 1.73%
Primary secondary mortgage rate spread | 105 |  | 104
Delinquency Rate | 2.55% |  | 2.73%

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- Definition Indicates the number of mortgage loans being serviced. + References No definition available. + Details
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- Definition Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Service Cost Minimum + References No definition available. + Details
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- Definition The escrow earning rate used to estimate the fair value of servicing assets, based on rates paid on deposit accounts. + References No definition available. + Details
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- Definition Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Maximum + References No definition available. + Details
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- Definition Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Minimum + References No definition available. + Details
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- Definition The maximum cost to service a performing loan for the period used as a variable in estimating fair value. + References No definition available. + Details
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- Definition The minimum cost to service a performing loan for the period used as a variable in estimating fair value. + References No definition available. + Details
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- Definition The maximum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. + References No definition available. + Details
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- Definition The minimum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. + References No definition available. + Details
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- Definition Represents the weighted average interest rate of loans servicedf for others as of the balance sheet date. + References No definition available. + Details
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- Definition Amount of increase (decrease) in fair value from changes in the assumptions or model used to calculate the fair value of a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References No definition available. + Details
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- Definition The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746 + Details
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- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746 + Details
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