Mortgage Servicing Rights - Summarized Corporation's Activity Related to Changes in Impairment Valuation Allowance of MSRs (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Balance, January 1	$ (1,808)	$ (1,787)	$ (1,760)
Impairment	(652)	(70)	(103)
Recovery	53	49	76
Balance, December 31	$ (2,407)	$ (1,808)	$ (1,787)

Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746

+ Details

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- Definition

Amount of increase in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from charges to expense.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746

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- Definition

Amount of decrease in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from recoveries recognized.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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