Carrying Amount and Fair Value of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Available-for-sale securities	$ 366,173	$ 326,117
Held-to-maturity securities	72,490	57,889
FDIC indemnification asset	20,844	27,900	$ 34,691
Accrued interest receivable	6,007	6,315
Derivative financial assets		5
Liabilities
Derivative financial liabilities	251	214
Carrying (Reported) Amount, Fair Value Disclosure
Assets
Cash and cash equivalents	51,787	237,660
Available-for-sale securities	366,173	326,117
Held-to-maturity securities	72,541	57,948
Loans held for sale		1,792
Loans held for investment less allowance	1,686,308	1,669,189
FDIC indemnification asset	20,844	27,900
Accrued interest receivable	6,007	6,315
Derivative financial assets		5
Deferred compensation assets	3,464	3,380
Liabilities
Securities sold under agreements to repurchase	138,614	121,742
Accrued interest payable	1,260	1,668
FHLB and other borrowings	80,756	107,999
Derivative financial liabilities	251	214
Deferred compensation liabilities	3,464	3,380
Carrying (Reported) Amount, Fair Value Disclosure \| Demand Deposits
Liabilities
Deposits Fair Value	451,511	417,729
Carrying (Reported) Amount, Fair Value Disclosure \| Interest-bearing Deposits
Liabilities
Deposits Fair Value	347,705	353,874
Carrying (Reported) Amount, Fair Value Disclosure \| Savings Deposits
Liabilities
Deposits Fair Value	530,585	525,478
Carrying (Reported) Amount, Fair Value Disclosure \| Bank Time Deposits
Liabilities
Deposits Fair Value	543,458	703,678
Estimate of Fair Value, Fair Value Disclosure
Assets
Cash and cash equivalents	51,787	237,660
Available-for-sale securities	366,173	326,117
Held-to-maturity securities	72,490	57,889
Loans held for sale		1,790
Loans held for investment less allowance	1,685,061	1,738,553
FDIC indemnification asset	10,753	18,040
Accrued interest receivable	6,007	6,315
Derivative financial assets		5
Deferred compensation assets	3,464	3,380
Liabilities
Securities sold under agreements to repurchase	140,880	123,114
Accrued interest payable	1,260	1,668
FHLB and other borrowings	85,774	116,599
Derivative financial liabilities	251	214
Deferred compensation liabilities	3,464	3,380
Estimate of Fair Value, Fair Value Disclosure \| Demand Deposits
Liabilities
Deposits Fair Value	451,511	417,729
Estimate of Fair Value, Fair Value Disclosure \| Interest-bearing Deposits
Liabilities
Deposits Fair Value	347,705	353,874
Estimate of Fair Value, Fair Value Disclosure \| Savings Deposits
Liabilities
Deposits Fair Value	530,585	525,478
Estimate of Fair Value, Fair Value Disclosure \| Bank Time Deposits
Liabilities
Deposits Fair Value	541,059	704,590
Level 1
Assets
Cash and cash equivalents	51,787	237,660
Available-for-sale securities	54	221
Deferred compensation assets	3,464	3,380
Liabilities
Deferred compensation liabilities	3,464	3,380
Level 2
Assets
Available-for-sale securities	366,119	325,896
Held-to-maturity securities	72,490	57,889
Loans held for sale		1,790
Loans held for investment less allowance	5,137	3,406
Accrued interest receivable	6,007	6,315
Derivative financial assets		5
Liabilities
Securities sold under agreements to repurchase	140,880	123,114
Accrued interest payable	1,260	1,668
FHLB and other borrowings	85,774	116,599
Derivative financial liabilities	251	214
Level 2 \| Demand Deposits
Liabilities
Deposits Fair Value	451,511	417,729
Level 2 \| Interest-bearing Deposits
Liabilities
Deposits Fair Value	347,705	353,874
Level 2 \| Savings Deposits
Liabilities
Deposits Fair Value	530,585	525,478
Level 2 \| Bank Time Deposits
Liabilities
Deposits Fair Value	541,059	704,590
Level 3
Assets
Loans held for investment less allowance	1,679,924	1,735,147
FDIC indemnification asset	$ 10,753	$ 18,040

Deferred compensation assets fair value.

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Deferred compensation liabilities fair value.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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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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Carrying amount of receivable assets originating from the indemnification agreement with the Federal Deposit Insurance Corporation (FDIC), in which the FDIC is to partially cover losses.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value of investments in debt securities classified as held-to-maturity.

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Amount of interest payable on debt, including, but not limited to, trade payables.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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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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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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