Fair Value Disclosures - Assets Measured at Fair Value on Non-recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	$ 516	$ 1,200
Total assets	317	1,779
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans held for investment	36,018	25,166
Impaired Leases Fair Value Disclosure	277
Other real estate owned	516	1,187
Total assets	36,811	26,353
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	36,018	25,166
Impaired Leases Fair Value Disclosure	277
Other real estate owned	516	1,187
Total assets	$ 36,811	$ 26,353