Fair Value Disclosures - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transfer between Level 2 and Level 3	$ 0	$ 0	$ 0	$ 0	$ 0
Impaired loans carrying value, recorded investment with allowance	17,682,000	14,701,000	17,682,000	14,701,000	16,213,000
Impaired loans valuation reserves	3,046,000	3,866,000	3,046,000	3,866,000	3,228,000
Impaired loans net fair value	14,636,000		14,636,000
Other real estate owned, total	$ 202,000	$ 635,000	$ 202,000	$ 635,000	$ 982,000
Minimum [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	5		5
Maximum [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	25		25