Credit Quality of Loans and Allowance for Loan Losses - Loan Portfolio and Concentrations (Details) $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($) industry_concentration	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)
Loan portfolio [Abstract]
Loans	$ 1,250,049	$ 1,263,645	$ 1,310,929
Less allowance for loan losses	(20,347)	(19,011)
Loans, net	$ 1,229,702	1,244,634
Number of industry segment concentration above threshold limit \| industry_concentration	1
Concentration risk, percentage	10.00%
Loans exposure in oil and gas industry	$ 252,500
Exposure in the oil and gas industry specified as percentage of total loans	20.20%
Loans with exposure in commercial real estate	$ 532,500
Loans on nonaccrual status	53,714	50,051
Commercial, financial and agricultural
Loan portfolio [Abstract]
Loans	441,160	454,028	484,508
Loans on nonaccrual status	24,900	27,705
Real estate - construction
Loan portfolio [Abstract]
Loans	84,790	74,952	76,964
Real estate – commercial
Loan portfolio [Abstract]
Loans	$ 467,648	471,141	471,737
Percentage of CRE loans secured by owner-occupied commercial properties	54.00%
Loans on nonaccrual status	$ 26,000
Nonaccrual status of loans specified as percentage of total CRE loans	4.90%
Real estate – residential
Loan portfolio [Abstract]
Loans	$ 149,961	149,064	153,647
Installment loans to individuals
Loan portfolio [Abstract]
Loans	103,181	111,009	115,284
Lease financing receivable
Loan portfolio [Abstract]
Loans	1,590	1,968	6,350
Loans on nonaccrual status	0	0
Other
Loan portfolio [Abstract]
Loans	1,719	1,483	$ 2,439
Loans on nonaccrual status	$ 0	$ 0

This line item represents the exposure in the oil and gas industry specified as a percentage of total loans.

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This line item represents the loans exposure in the oil and gas industry.

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This line item represents the loans with exposure in the commercial real estate section.

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This line item represents the percentage of nonaccrual status of loans specified as percentage of total CRE loans.

+ References

No definition available.

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This line item represents the number of industry segment concentration above threshold limit of the loan portfolio.

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This line item represents the percentage of CRE loans secured by owner occupied commercial properties.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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