Fair Value Disclosures - Assets Measured at Fair Value on Non-recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 7,400	$ 516
Total assets	187	317
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans held for investment	30,900	36,018
Impaired Leases Fair Value Disclosure		277
Other real estate owned	7,355	516
Total assets	38,255	36,811
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans held for investment	0	0
Impaired Leases Fair Value Disclosure		0
Other real estate owned	0	0
Total assets	0	0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans held for investment	0	0
Impaired Leases Fair Value Disclosure		0
Other real estate owned	0	0
Total assets	0	0
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans held for investment	30,900	36,018
Impaired Leases Fair Value Disclosure		277
Other real estate owned	7,355	516
Total assets	$ 38,255	$ 36,811