Mortgage Servicing Rights - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Unpaid principal balance of mortgage loans serviced for others	$ 287.3		$ 304.3
Minimum [Member]
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Discount rates used in valuation model	10.10%	9.50%
Prepayment speeds used in valuation model	6.90%	7.70%
Maximum [Member]
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Discount rates used in valuation model	13.00%	13.00%
Prepayment speeds used in valuation model	36.70%	38.20%