Fair Value Measurements - Financial Assets and Financial Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale, at estimated fair value	$ 127,308	$ 100,717
Equity investments	10,145	9,655
Interest rate swap liability	15,200	1,800
Other real estate owned	294	1,381
Items measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale, at estimated fair value	127,308	100,717
Equity investments	10,145	9,655
Interest rate swap asset	14,477	1,722
Interest rate swap liability	(15,170)	(1,813)
Items measured on a recurring basis | Level 1 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale, at estimated fair value	0	0
Equity investments	10,145	9,655
Interest rate swap asset	0	0
Interest rate swap liability	0	0
Items measured on a recurring basis | Level 2 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale, at estimated fair value	127,308	100,717
Equity investments	0	0
Interest rate swap asset	14,477	1,722
Interest rate swap liability	(15,170)	(1,813)
Items measured on a recurring basis | Level 3 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale, at estimated fair value	0	0
Equity investments	0	0
Interest rate swap asset	0	0
Interest rate swap liability	0	0
Items measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	294	1,381
Items measured on a recurring basis | Loans measured for impairment based on the fair value of the underlying collateral
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	8,983	11,639
Items measured on a recurring basis | Level 1 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	0	0
Items measured on a recurring basis | Level 1 Inputs | Loans measured for impairment based on the fair value of the underlying collateral
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0
Items measured on a recurring basis | Level 2 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	0	0
Items measured on a recurring basis | Level 2 Inputs | Loans measured for impairment based on the fair value of the underlying collateral
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	0	0
Items measured on a recurring basis | Level 3 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	294	1,381
Items measured on a recurring basis | Level 3 Inputs | Loans measured for impairment based on the fair value of the underlying collateral
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	$ 8,983	$ 11,639