Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest-bearing deposits maturing date	90 days
Collateral dependent impaired loans categorized as Level 3	$ 2,169	$ 2,054	$ 1,606
Specific allocation for collateral dependent impaired loans	59	31	$ 104
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans categorized as Level 3	$ 195	$ 215