Credit Quality of Loans and Allowance for Loan Losses - Summary of Loan Portfolio (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Loan portfolio [Abstract]
Ending balance	$ 1,137,255	$ 1,183,426	$ 1,272,000
Less allowance for loan losses	(25,371)	(26,888)
Loans, net	1,111,884	1,156,538
Commercial, financial and agricultural
Loan portfolio [Abstract]
Ending balance	401,048	435,207	469,815
Real estate - construction
Loan portfolio [Abstract]
Ending balance	94,679	90,287	100,248
Real estate – commercial
Receivables [Abstract]
Total CRE loans on non-accrual	26,200
Loan portfolio [Abstract]
Ending balance	438,779	448,406	464,859
Real estate – residential
Loan portfolio [Abstract]
Ending balance	145,671	146,751	159,426
Installment loans to individuals
Loan portfolio [Abstract]
Ending balance	50,888	56,398	75,258
Lease financing receivable
Loan portfolio [Abstract]
Ending balance	692	732	969
Other
Loan portfolio [Abstract]
Ending balance	$ 5,498	$ 5,645	$ 1,425

Total CRE loans on non-accrual

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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.

+ References

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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.

+ References

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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