Equity Incentive Plan - Summary of Company's Outstanding Restricted Stock (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2021 USD ($) $ / shares shares
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted	73,138
Expected future remaining compensation expense \| $	$ 1,134
Expected future compensation expense, restricted shares remaining vesting period	3 years 21 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 \| $	$ 18
Expected future compensation expense, restricted shares remaining vesting period	9 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 \| $	$ 54
Expected future compensation expense, restricted shares remaining vesting period	1 year 9 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 \| $	$ 48
Expected future compensation expense, restricted shares remaining vesting period	9 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 \| $	$ 109
Expected future compensation expense, restricted shares remaining vesting period	2 years 9 months
Restricted Shares Awarded on March 14, 2020 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted	9,336
Date of Award	Mar. 14, 2020
Expected future remaining compensation expense \| $	$ 163
Expected future compensation expense, restricted shares remaining vesting period	1 year 9 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 \| $	$ 185
Expected future compensation expense, restricted shares remaining vesting period	3 years 9 months
Restricted Shares Awarded on March 3, 2021 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted	16,799
Date of Award	Mar. 03, 2021
Expected future remaining compensation expense \| $	$ 286
Expected future compensation expense, restricted shares remaining vesting period	4 years 9 months
Restricted Shares Awarded on March 3, 2021 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted	22,340
Date of Award	Mar. 03, 2021
Expected future remaining compensation expense \| $	$ 271
Expected future compensation expense, restricted shares remaining vesting period	2 years 9 months
Restricted Stock [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Nonvested at beginning of period	54,274
Number of Restricted Shares, Granted	39,139
Number of Restricted Shares, Vested	(20,275)
Number of Restricted Shares, Forfeited	0
Number of Restricted Shares, Nonvested at end of period	73,138
Weighted Average Grant Date Fair Value, Nonvested at beginning of period \| $ / shares	$ 20.90
Weighted Average Grant Date Fair Value, Granted \| $ / shares	19.17
Weighted Average Grant Date Fair Value, Vested \| $ / shares	20.35
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	0
Weighted Average Grant Date Fair Value, Nonvested at end of period \| $ / shares	$ 20.13

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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