Equity Incentive Plan - Summary of Company's Outstanding Restricted Stock (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		72,071
Expected future remaining compensation expense | $	$ 1,121	$ 1,121
Expected future compensation expense, restricted shares remaining vesting period		2 years 9 months 18 days
Restricted Shares Awarded on March 20, 2017 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		1,198
Date of Award		Mar. 20, 2017
Expected future remaining compensation expense | $	14	$ 14
Expected future compensation expense, restricted shares remaining vesting period		6 months
Restricted Shares Awarded on April 10, 2018 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		3,114
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense | $	46	$ 46
Expected future compensation expense, restricted shares remaining vesting period		1 year 6 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		3,401
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense | $	32	$ 32
Expected future compensation expense, restricted shares remaining vesting period		6 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		6,560
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense | $	99	$ 99
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 months
Restricted Shares Awarded on March 14, 2020 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		9,139
Date of Award		Mar. 14, 2020
Expected future remaining compensation expense | $	135	$ 135
Expected future compensation expense, restricted shares remaining vesting period		1 year 6 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		10,390
Date of Award		Mar. 14, 2020
Expected future remaining compensation expense | $	172	$ 172
Expected future compensation expense, restricted shares remaining vesting period		3 years 6 months
Restricted Shares Awarded on March 3, 2021 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		16,277
Date of Award		Mar. 03, 2021
Expected future remaining compensation expense | $	259	$ 259
Expected future compensation expense, restricted shares remaining vesting period		4 years 6 months
Restricted Shares Awarded on March 3, 2021 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		21,992
Date of Award		Mar. 03, 2021
Expected future remaining compensation expense | $	$ 364	$ 364
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 months
Restricted Stock [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Nonvested at beginning of period	73,138	54,274
Number of Restricted Shares, Granted	0	39,139
Number of Restricted Shares, Vested	0	(20,275)
Number of Restricted Shares, Forfeited	(1,067)	(1,067)
Number of Restricted Shares, Nonvested at end of period	72,071	72,071
Weighted Average Grant Date Fair Value, Nonvested at beginning of period | $ / shares	$ 20.13	$ 20.90
Weighted Average Grant Date Fair Value, Granted | $ / shares	0	19.17
Weighted Average Grant Date Fair Value, Vested | $ / shares	0	20.35
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	19.56	19.56
Weighted Average Grant Date Fair Value, Nonvested at end of period | $ / shares	$ 20.13	$ 20.13