Equity Incentive Plan - Summary of Company's Outstanding Restricted Stock (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		44,027
Expected future remaining compensation expense \| $	$ 577	$ 577
Expected future compensation expense, restricted shares remaining vesting period		2 years 6 months
Restricted Shares Awarded on January 15, 2016 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		4,108
Date of Award		Jan. 15, 2016
Expected future remaining compensation expense \| $	26	$ 26
Expected future compensation expense, restricted shares remaining vesting period		1 year 3 months
Restricted Shares Awarded on March 20, 2017 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		3,725
Date of Award		Mar. 20, 2017
Expected future remaining compensation expense \| $	12	$ 12
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		3,581
Date of Award		Mar. 20, 2017
Expected future remaining compensation expense \| $	55	$ 55
Expected future compensation expense, restricted shares remaining vesting period		2 years 3 months
Restricted Shares Awarded on April 10, 2018 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		5,282
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense \| $	60	$ 60
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		6,225
Date of Award		Apr. 10, 2018
Expected future remaining compensation expense \| $	101	$ 101
Expected future compensation expense, restricted shares remaining vesting period		3 years 3 months
Restricted Shares Awarded on March 14, 2019 [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Granted		10,188
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense \| $	153	$ 153
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		10,918
Date of Award		Mar. 14, 2019
Expected future remaining compensation expense \| $	$ 170	$ 170
Expected future compensation expense, restricted shares remaining vesting period		4 years 3 months
Restricted Stock [Member]
Schedule Of Nonvested Stock Option Activity [Line Items]
Number of Restricted Shares, Nonvested at beginning of period	44,027	39,970
Number of Restricted Shares, Granted	0	21,106
Number of Restricted Shares, Vested	0	(16,557)
Number of Restricted Shares, Forfeited	0	(492)
Number of Restricted Shares, Nonvested at end of period	44,027	44,027
Weighted Average Grant Date Fair Value, Nonvested at beginning of period \| $ / shares	$ 20.48	$ 19.10
Weighted Average Grant Date Fair Value, Granted \| $ / shares	0	20.65
Weighted Average Grant Date Fair Value, Vested \| $ / shares	0	17.31
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	0	22.41
Weighted Average Grant Date Fair Value, Nonvested at end of period \| $ / shares	$ 20.48	$ 20.48

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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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