Securities - Summary of Securities Available-for-Sale and Restricted Stock (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2020
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	$ 111,052	$ 111,874
Gross Unrealized Gains, Available-for-sale	1,763	701
Gross Unrealized Losses, Available-for-sale	(536)	(429)
Available-for-sale, at fair value	112,279	112,146
Amortized Cost, Held to maturity	9,901	13,869
Gross Unrealized Gains, Held to maturity	231	143
Gross Unrealized Losses, Held to maturity	(12)	(62)
Fair Value, Held to maturity	10,120	13,950
Amortized Cost	125,620	130,410
Gross Unrealized Gains	2,023	883
Gross Unrealized Losses	(548)	(491)
Fair Value	127,095	130,802
U.S. Treasury Security [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	999	998
Gross Unrealized Gains, Available-for-sale	16	1
Available-for-sale, at fair value	1,015	999
U.S. Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale		5,500
Gross Unrealized Losses, Available-for-sale		(4)
Available-for-sale, at fair value		5,496
Amortized Cost, Held to maturity		4,999
Gross Unrealized Losses, Held to maturity		(6)
Fair Value, Held to maturity		4,993
Mortgage-Backed Securities of Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	75,440	75,676
Gross Unrealized Gains, Available-for-sale	1,148	326
Gross Unrealized Losses, Available-for-sale	(200)	(145)
Available-for-sale, at fair value	76,388	75,857
Amortized Cost, Held to maturity	6,476	8,870
Gross Unrealized Gains, Held to maturity	231	143
Gross Unrealized Losses, Held to maturity	(12)	(56)
Fair Value, Held to maturity	6,695	8,957
Asset-Backed Securities of Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	868	934
Gross Unrealized Losses, Available-for-sale	(62)	(17)
Available-for-sale, at fair value	806	917
State and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	25,259	21,161
Gross Unrealized Gains, Available-for-sale	563	351
Gross Unrealized Losses, Available-for-sale		(1)
Available-for-sale, at fair value	25,822	21,511
Amortized Cost, Held to maturity	3,425
Fair Value, Held to maturity	3,425
Corporate Bonds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Available-for-sale	8,486	7,605
Gross Unrealized Gains, Available-for-sale	36	23
Gross Unrealized Losses, Available-for-sale	(274)	(262)
Available-for-sale, at fair value	8,248	7,366
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost, Equity securities		53	$ 53
Gross Unrealized Gains, Equity securities	29	39
Fair Value, Equity securities		92	$ 82
Restricted Stock [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	4,614	4,614
Fair Value	$ 4,614	$ 4,614

Equity securities, FV-NI, cost with and without readily determinable value.

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Equity securities, FV-NI, unrealized gain with and without readily determinable value.

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Marketable Securities Amortized Cost

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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