Credit Quality of Loans and Allowance for Loan Losses, Aggregate Allowance for Loan Losses and Related Party Lending (Details) (USD $)	9 Months Ended
	Sep. 30, 2014 Segment	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of industry segment concentration above threshold limit	1
Threshold percentage of loan portfolio (in hundredths)	10.00%
Loans exposure in oil and gas industry	$ 255,600,000
Exposure in oil and gas industry specified as percentage of total loans (in hundredths)	20.50%
Loans with exposure in commercial real estate	491,300,000
Loans on nonaccrual status	7,750,000	5,099,000
Commercial, Financial and Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans on nonaccrual status	2,649,000	1,272,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans with exposure in commercial real estate	395,100,000
Percentage of CRE loans secured by owner-occupied commercial properties (in hundredths)	63.20%
Loans on nonaccrual status	3,400,000
Nonaccrual status of loans specified as percentage of total CRE loans (in hundredths)	0.90%
Finance Leases Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans on nonaccrual status	0	0
Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans on nonaccrual status	$ 0	$ 0