Credit Quality of Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) Contract	Jun. 30, 2014 Contract	Jun. 30, 2015 USD ($) Contract	Jun. 30, 2014 USD ($) Contract	Dec. 31, 2014 USD ($)
Financing Receivable, Modifications [Line Items]
Current	$ 21,529,000		$ 21,529,000		$ 176,000
Past Due Greater Than 30 Days	0		0		0
Nonaccrual TDRs	234,000		234,000		234,000
Total TDRs	$ 21,763,000		$ 21,763,000		410,000
Pre-modified contracts identified as TDRs | Contract	1	0	1	1
Pre-modification balance identified as TDR	$ 21,400,000		$ 21,400,000	$ 1,200,000
Number of TDR defaulted | Contract	0	0	0	0
Commitments to lend additional funds	$ 0		$ 0
Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Current	21,377,000		21,377,000		21,000
Past Due Greater Than 30 Days	0		0		0
Nonaccrual TDRs	234,000		234,000		234,000
Total TDRs	21,611,000		21,611,000		255,000
Real estate – commercial
Financing Receivable, Modifications [Line Items]
Current	152,000		152,000		155,000
Past Due Greater Than 30 Days	0		0		0
Nonaccrual TDRs	0		0		0
Total TDRs	$ 152,000		$ 152,000		$ 155,000