Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Commitments to lend additional funds to borrowers	$ 100	$ 808
Maximum
Schedule Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Standby letters of credit	17,200	21,600
Commitments to Extend Credit
Schedule Of Financial Instruments With Off Balance Sheet Credit Risk [Line Items]
Financial instruments with off-balance sheet risks, contract amount	$ 1,100,000	$ 973,700