Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Loans And Leases Receivable [Line Items]
Loans and leases, net of unearned discount	$ 89,800	$ 124,785	$ 231,516	$ 507,582
Amount of foreclosed residential real estate property held	36,000		36,000		$ 24,000
Loans secured by residential real estate that were in the process of foreclosure	$ 187,000		$ 187,000		151,000
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	46.00%		46.00%
Loans pledged to secure outstanding borrowings	$ 123,740,992		$ 123,740,992		89,043,040
Minimum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period			90 days
Maximum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period			150 days
Commercial Real Estate [Member] | Asset Pledged as Collateral without Right [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings	13,900,000		$ 13,900,000		11,900,000
Residential Mortgage Loans [Member] | Asset Pledged as Collateral without Right [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings	18,700,000		18,700,000		11,500,000
Residential Mortgage Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	43,000		43,000		474,000
Commercial Real Estate Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	300,000		300,000		425,000
Commercial Loans And Leases [Member] | Asset Pledged as Collateral without Right [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings	9,900,000		9,900,000		9,500,000
Home Equity Line of Credit [Member] | Asset Pledged as Collateral without Right [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings	3,100,000		3,100,000		1,900,000
Other Consumer Loans [Member] | Asset Pledged as Collateral without Right [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings	10,400,000		10,400,000		10,200,000
Commercial Loans and Commercial Real Estate [Member] | Minimum [Member]
Loans And Leases Receivable [Line Items]
Amount of real estate loan as reported as accruing or nonaccruing	1,000		1,000
COVID-19 [Member] | Government-Guaranteed Loans [Member]
Loans And Leases Receivable [Line Items]
Loans and leases, net of unearned discount			20,000		974,000
Payment Deferral [Member]
Loans And Leases Receivable [Line Items]
Loans and leases, net of unearned discount	$ 48,275	$ 56,116	160,742	$ 196,378
Payment Deferral [Member] | COVID-19 [Member] | Residential Real Estate [Member]
Loans And Leases Receivable [Line Items]
Loans and leases, net of unearned discount			$ 39,000		$ 1,200,000