Mortgage Servicing Rights - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Unpaid principal balance of mortgage loans serviced for others	$ 342.6	$ 345.1
Minimum [Member]
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Discount rates used in valuation model	10.00%
Prepayment speeds used in valuation model	14.60%
Maximum [Member]
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Discount rates used in valuation model	13.50%
Prepayment speeds used in valuation model	44.70%

Unpaid Principal Balance of Loans Serviced for Others

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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.

+ 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

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