Credit Quality of Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 contract	Jun. 30, 2016 USD ($) contract	Jun. 30, 2015 USD ($) contract	Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items]
Current	$ 154,000		$ 154,000		$ 16,000
Past Due Greater Than 30 Days	0		0		148,000
Nonaccrual TDRs	26,224,000		26,224,000		20,865,000
Total TDRs	$ 26,378,000		$ 26,378,000		21,029,000
Pre-modified contracts identified as TDRs (contracts) | contract	0	1	1	1
Number of TDR defaulted (contracts) | contract	0	0	1	0
TDRs defaulted, amount			$ 5,500,000
Pre-modification balance identified as TDR			5,500,000	$ 21,400,000
Commitments to lend additional funds	$ 0		0
Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Current	14,000		14,000		16,000
Past Due Greater Than 30 Days	0		0		0
Nonaccrual TDRs	24,652,000		24,652,000		20,865,000
Total TDRs	24,666,000		24,666,000		20,881,000
Real estate – commercial
Financing Receivable, Modifications [Line Items]
Current	140,000		140,000		0
Past Due Greater Than 30 Days	0		0		148,000
Nonaccrual TDRs	1,572,000		1,572,000		0
Total TDRs	$ 1,712,000		$ 1,712,000		$ 148,000