Impaired Loans and Allowance for Loan Losses - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Newly identified TDRs	$ 2,600,000
Troubled Debt Restructuring Outstanding	20,000,000	$ 25,000,000
Loans and Leases Receivable, Impaired, Troubled Debt, Interest Income	880,000	1,345,000	$ 1,260,000
Loans and Leases Receivable, Impaired, Interest Income Recognized, Change in Present Value Attributable to Passage of Time	$ 318,000	456,000	1,100,000
Loan Default Period	90 days
Impaired Financing Receivable, Average Recorded Investment	$ 38,514,000	49,602,000	66,600,000
Nonaccrual loans and loans past due ninety days	17,386,000	21,140,000	27,672,000
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	17,000	160,000
Provision for Loan, Lease, and Other Losses	2,644,000	(3,486,000)	3,188,000
Allowance for Loan and Lease Losses, Write-offs	3,599,000	2,755,000	6,784,000
Financing Receivable, Recorded Investment, Past Due	0	196,000
Purchased Unimpaired Loans [Member]
Financing Receivable, Modifications [Line Items]
Provision for Loan, Lease, and Other Losses	1,300,000
Allowance for Loan and Lease Losses, Write-offs	$ 1,200,000
Purchased Loans [Member]
Financing Receivable, Modifications [Line Items]
Loan Default Period	90 days
Nonaccrual loans and loans past due ninety days	$ 4,628,000	2,577,000
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	196,000
Financing Receivable, Recorded Investment, Past Due	4,628,000,000	2,577,000,000
Commercial Portfolio Segment Real Estate Loan [Member]
Financing Receivable, Modifications [Line Items]
Newly identified TDRs	1,900,000
Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Nonaccrual loans and loans past due ninety days	12,758,000,000	18,563,000,000	27,672,000,000
Financing Receivable, Recorded Investment, Past Due	4,628,000	2,577,000
Construction and Land Development [Member]
Financing Receivable, Modifications [Line Items]
Newly identified TDRs	200,000
Impaired Financing Receivable, Average Recorded Investment	2,239,000	3,293,000
Provision for Loan, Lease, and Other Losses	1,296,000	139,000	66,000
Allowance for Loan and Lease Losses, Write-offs	1,271,000	640,000	$ 604,000
Loans [Member] | The Bank shares Inc [Member]
Financing Receivable, Modifications [Line Items]
Assets, Fair Value Adjustment	$ 14,200,000	$ 11,200,000
Fair value adjustment Percent	4.43%	3.56%