Fair Value of Financial Instruments - Summary of Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 86,131	$ 58,492
Interest-earning time deposits	15,987	15,744
Investment securities, held to maturity	206,327	210,112
Loans held for sale	1,979	1,038
Loans (excluding loan level hedges), net	3,615,681	3,005,305
Stock in FHLB	22,447	18,073
Interest receivable	17,423	14,239
Liabilities
Non-interest bearing deposits	811,768	642,129
Interest bearing deposits	3,076,255	2,497,247
Borrowings	457,788	550,384
Subordinated debentures	55,310	37,837
Interest payable	2,471	2,031
Carrying Amount [Member]
Assets
Cash and due from banks	86,131	58,492
Interest-earning time deposits	15,987	15,744
Investment securities, held to maturity	206,327	210,112
Loans held for sale	1,979	1,038
Loans (excluding loan level hedges), net	3,368,911	2,786,351
Stock in FHLB	22,447	18,073
Interest receivable	17,423	14,239
Liabilities
Non-interest bearing deposits	811,768	642,129
Interest bearing deposits	3,076,255	2,497,247
Borrowings	457,788	550,384
Subordinated debentures	55,310	37,837
Interest payable	2,471	2,031
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets
Cash and due from banks	86,131	58,492
Liabilities
Non-interest bearing deposits	811,768	642,129
Significant Other Observable Inputs (Level 2) [Member]
Assets
Interest-earning time deposits		15,542
Investment securities, held to maturity	210,106	208,273
Stock in FHLB	22,447	18,073
Interest receivable	17,423	14,239
Liabilities
Interest bearing deposits	3,005,839	2,377,274
Borrowings	412,884	542,311
Subordinated debentures	49,568	35,711
Interest payable	2,471	2,031
Significant Unobservable Inputs (Level 3) [Member]
Assets
Loans held for sale	1,979	1,038
Loans (excluding loan level hedges), net	$ 3,267,463	$ 2,681,741

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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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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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