Equity Incentive Plan - Summary of Company's Outstanding Restricted Stock (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		54,274
Expected future remaining compensation expense | $	$ 751	$ 751
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 months 18 days
Restricted Shares Awarded on January 15, 2016 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		2,056
Date of Award		Jan. 15, 2016
Expected future remaining compensation expense | $	5	$ 5
Expected future compensation expense, restricted shares remaining vesting period		3 months
Restricted Shares Awarded on March 20, 2017 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		2,388
Date of Award		Mar. 20, 2017
Expected future remaining compensation expense | $	31	$ 31
Expected future compensation expense, restricted shares remaining vesting period		1 year 3 months
Restricted Shares Awarded on April 10, 2018 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		2,643
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense | $	11	$ 11
Expected future compensation expense, restricted shares remaining vesting period		3 months
Restricted Shares Awarded on April 10, 2018 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		4,670
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense | $	70	$ 70
Expected future compensation expense, restricted shares remaining vesting period		2 years 3 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		6,796
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense | $	79	$ 79
Expected future compensation expense, restricted shares remaining vesting period		1 year 3 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		8,742
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense | $	129	$ 129
Expected future compensation expense, restricted shares remaining vesting period		3 years 3 months
Restricted Shares Awarded on March 13, 2020 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		12,982
Date of Award		Mar. 13, 2020
Expected future remaining compensation expense | $	212	$ 212
Expected future compensation expense, restricted shares remaining vesting period		4 years 3 months
Restricted Shares Awarded on March 13, 2020 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		13,997
Date of Award		Mar. 13, 2020
Expected future remaining compensation expense | $	$ 214	$ 214
Expected future compensation expense, restricted shares remaining vesting period		2 years 3 months
Restricted Stock [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Nonvested at beginning of period	54,274	44,027
Number of Restricted Shares, Granted	0	26,979
Number of Restricted Shares, Vested	0	(16,732)
Number of Restricted Shares, Forfeited	0	0
Number of Restricted Shares, Nonvested at end of period	54,274	54,274
Weighted Average Grant Date Fair Value, Nonvested at beginning of period | $ / shares	$ 20.90	$ 20.48
Weighted Average Grant Date Fair Value, Granted | $ / shares	0	21.26
Weighted Average Grant Date Fair Value, Vested | $ / shares	0	20.36
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	0	0
Weighted Average Grant Date Fair Value, Nonvested at end of period | $ / shares	$ 20.90	$ 20.90