Fair Value Measurement - Estimated Fair Values of Financial Instruments that are Reported at Amortized Cost in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financial assets:
Cash and due from banks	$ 94,661	$ 105,968
Cash at Federal Reserve and other banks	89,401	99,460
Securities held to maturity	477,745	514,844
Financial liabilities:
Other borrowings	152,839	122,166
Junior subordinated debt	56,950	56,858
Level 3 [Member] \| Overdraft Privilege Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	97,670	98,260
Level 3 [Member] \| Standby Letters of Credit [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	11,535	13,075
Level 3 [Member] \| Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	994,944	933,542
Fair Value [Member] \| Level 3 [Member]
Financial assets:
Loans, net	3,091,134	2,992,225
Financial liabilities:
Junior subordinated debt	58,930	58,466
Fair Value [Member] \| Level 3 [Member] \| Overdraft Privilege Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	977	983
Fair Value [Member] \| Level 3 [Member] \| Standby Letters of Credit [Member]
Off-balance sheet:
Fair value, Off-balance sheet	115	131
Fair Value [Member] \| Level 3 [Member] \| Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	9,949	9,335
Fair Value [Member] \| Level 1 [Member]
Financial assets:
Cash and due from banks	94,661	105,968
Cash at Federal Reserve and other banks	89,401	99,460
Fair Value [Member] \| Level 2 [Member]
Financial assets:
Securities held to maturity	468,621	518,165
Loans held for sale	3,601	4,616
Financial liabilities:
Deposits	4,073,628	4,006,620
Other borrowings	152,839	122,166
Carrying Amount [Member] \| Level 3 [Member]
Financial assets:
Loans, net	3,116,789	2,984,842
Financial liabilities:
Junior subordinated debt	56,950	56,858
Carrying Amount [Member] \| Level 1 [Member]
Financial assets:
Cash and due from banks	94,661	105,968
Cash at Federal Reserve and other banks	89,401	99,460
Carrying Amount [Member] \| Level 2 [Member]
Financial assets:
Securities held to maturity	477,745	514,844
Restricted equity securities	16,956	16,956
Loans held for sale	3,601	4,616
Financial liabilities:
Deposits	4,077,222	4,009,131
Other borrowings	$ 152,839	$ 122,166

Cash at federal reserve and other banks.

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Off balance sheet.

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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
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-Paragraph 1A
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The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

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The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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