Mortgage Servicing Rights - Quantitative Assumptions Used for MSRs (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Minimum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	12.79%	10.74%
Life in years (of the MSR)	1 year 11 months 23 days	2 years 14 days
Weighted-average coupon rate (as a percent)	3.56%	3.96%
Discount rate (as a percent)	10.00%	10.00%
Maximum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	23.29%	23.39%
Life in years (of the MSR)	6 years 3 months 21 days	6 years 3 months 29 days
Weighted-average coupon rate (as a percent)	7.04%	7.26%
Discount rate (as a percent)	10.00%	10.01%
Weighted Average
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	17.27%	11.10%
Life in years (of the MSR)	4 years 3 months 29 days	5 years 11 months 26 days
Weighted-average coupon rate (as a percent)	3.92%	4.01%
Discount rate (as a percent)	10.00%	10.00%

Weighted average coupon rate used to estimate the fair value of servicing assets and servicing liabilities.

No definition available.

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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

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- Definition

Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

+ References

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- Definition

Weighted average life of financial assets and financial liabilities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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