Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfer of assets into or out of level 3	$ 0	$ 0
Transfer of liabilities into or out of level 3	0	0
Collateral dependent impaired loans categorized as Level 3	14,532,000	3,061,000
Specific allocation for collateral dependent impaired loans	1,657,000	197,000
Asset impairment charges	0
Collateral Dependent [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific allocation for collateral dependent impaired loans	1,657,000	197,000
Level 3 [Member] | Collateral Dependent [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans categorized as Level 3	$ 7,703,000	$ 444,000