Mortgage Servicing Rights - Quantitative Assumptions Used for MSRs (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Minimum
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	15.12%	11.86%
Life in years (of the MSR)	1 year 11 months 12 days	1 year 9 months 29 days
Weighted-average coupon rate (as a percent)	3.60%	3.24%
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)	25.14%	26.52%
Life in years (of the MSR)	5 years 7 days	6 years 8 months 4 days
Weighted-average coupon rate (as a percent)	6.65%	6.98%
Discount rate (as a percent)	10.01%	10.00%
Weighted Average
Quantitative assumptions used in determining lower of cost or fair value of MSRs
Conditional prepayment rate (as a percent)	16.13%	16.90%
Life in years (of the MSR)	4 years 8 months 12 days	4 years 5 months 12 days
Weighted-average coupon rate (as a percent)	3.73%	3.84%
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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