Fair Value - Summary of Estimated Fair Values and Related Carrying amounts of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial Assets
Cash and due from banks	$ 117,945	$ 60,026	$ 15,026
Securities available for sale	109,475	108,571
Restricted equity investments	11,173	8,134
Cash surrender value of life insurance	15,724	15,321
Securities held to maturity		12,192
Cash surrender value of life insurance	15,724	15,321
Financial Liabilities
Noninterest-bearing deposits	333,051	177,819
FHLB borrowings	115,000	124,800
Subordinated debentures, net	24,506	9,800
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial Assets
Cash and due from banks	117,945	60,026
Federal funds sold	775	480
Financial Liabilities
Noninterest-bearing deposits	333,051	177,819
Significant Observable Inputs (Level 2) [Member]
Financial Assets
Securities available for sale	109,475	108,571
Restricted equity investments	11,173	8,143
Accrued interest receivable	5,428	2,590
Cash surrender value of life insurance	15,724	15,321
Securities held to maturity		12,654
Cash surrender value of life insurance	15,724	15,321
Financial Liabilities
Interest-bearing deposits	360,615	364,986
FHLB borrowings	114,983	124,971
FRB borrowings	281,650
Accrued interest payable	626	706
Significant Unobservable Inputs (Level 3) [Member]
Financial Assets
PPP loans receivable, net	288,533
Loans held for investment, net	690,007	643,878
Financial Liabilities
Interest-bearing deposits	257,647	168,736
Subordinated debentures, net	25,830	9,874
Carrying Amount
Financial Assets
Cash and due from banks	117,945	60,026
Federal funds sold	775	480
Securities available for sale	109,475	108,571
Restricted equity investments	11,173	8,143
PPP loans receivable, net	288,533
Loans held for investment, net	688,667	642,262
Accrued interest receivable	5,428	2,590
Cash surrender value of life insurance	15,724	15,321
Securities held to maturity		12,192
Cash surrender value of life insurance	15,724	15,321
Financial Liabilities
Noninterest-bearing deposits	333,051	177,819
Interest-bearing deposits	612,058	544,211
FHLB borrowings	115,000	124,800
FRB borrowings	281,650
Subordinated debentures, net	24,506	9,800
Accrued interest payable	626	706
Fair Value
Financial Assets
Cash and due from banks	117,945	60,026
Federal funds sold	775	480
Securities available for sale	109,475	108,571
Restricted equity investments	11,173	8,143
PPP loans receivable, net	288,533
Loans held for investment, net	690,007	643,878
Accrued interest receivable	5,428	2,590
Cash surrender value of life insurance	15,724	15,321
Securities held to maturity		12,654
Cash surrender value of life insurance	15,724	15,321
Financial Liabilities
Noninterest-bearing deposits	333,051	177,819
Interest-bearing deposits	618,262	533,722
FHLB borrowings	114,983	124,971
FRB borrowings	281,650
Subordinated debentures, net	25,830	9,874
Accrued interest payable	$ 626	$ 706

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Advances from federal reserve banks.

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Fair value portion of accrued expenses.

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

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Amount of restricted investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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