Equity Incentive Plan - Summary of Company's Outstanding Restricted Stock (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020 USD ($) $ / shares shares	Jun. 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 \| $	$ 849	$ 849
Expected future compensation expense, restricted shares remaining vesting period		2 years 9 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 \| $	10	$ 10
Expected future compensation expense, restricted shares remaining vesting period		6 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 \| $	37	$ 37
Expected future compensation expense, restricted shares remaining vesting period		1 year 6 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 \| $	23	$ 23
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		4,670
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense \| $	77	$ 77
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 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 \| $	95	$ 95
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		8,742
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense \| $	139	$ 139
Expected future compensation expense, restricted shares remaining vesting period		3 years 6 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 \| $	242	$ 242
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 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 \| $	$ 226	$ 226
Expected future compensation expense, restricted shares remaining vesting period		4 years 6 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

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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 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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