Commitments and Letters of Credit - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Notional amount of financial standby letters of credit	$ 900,000
Notional amount of performance standby letters of credit	7,000,000.0
Notional amount of commercial letters of credit	0
Financial instrument of credit risk	100,000	$ 200,000
Unused commitments and letters of credit [Member]
Loss Contingencies [Line Items]
Commitment liability	$ 4,500,000	$ 5,000,000.0