Financial Instruments With Off-Balance Sheet Risk - Summary of Outstanding Contract Amounts of Off Balance Sheet Credit Risk Related Financial Instruments (Detail) - Unfunded Loan Commitment [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule Of Loans And Leases Receivable Unfunded Commitments Under Line Of Credit [Line Items]
Unfunded commitments under lines of credit	$ 158,224	$ 47,214
Home equity loans [Member]
Schedule Of Loans And Leases Receivable Unfunded Commitments Under Line Of Credit [Line Items]
Unfunded commitments under lines of credit	16,917	6,815
Commercial real estate, construction, and land development [Member]
Schedule Of Loans And Leases Receivable Unfunded Commitments Under Line Of Credit [Line Items]
Unfunded commitments under lines of credit	23,297	3,801
Commercial and industrial [Member]
Schedule Of Loans And Leases Receivable Unfunded Commitments Under Line Of Credit [Line Items]
Unfunded commitments under lines of credit	113,347	35,517
Other [Member]
Schedule Of Loans And Leases Receivable Unfunded Commitments Under Line Of Credit [Line Items]
Unfunded commitments under lines of credit	$ 4,663	$ 1,081