Acquisitions and FDIC Indemnification Asset (Details Textual) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2016
Business Acquisition [Line Items]
Gain on Sale of certain assets and liabilities of Insurance Brokerage Operation	$ (199,000)	$ 0	$ 12,822,000	$ 0
Assets	3,019,323,000		3,019,323,000		$ 2,979,585,000
Goodwill	34,355,000		34,355,000		39,489,000
Loans and Leases Receivable, Net of Loans with Deteriorated Credit Quality, Covered	$ 6,000,000		6,000,000		6,500,000
First National Bank Of Danville [Member]
Business Acquisition [Line Items]
Reimbursements from the FDIC			19,500,000
Business Aquisition, Loss Sharing Agreement Losses On Assets Threshold			$ 29,000,000
Business Acquisition Loss Sharing Agreement Losses In Excess Of Threshold To Be Reimbursed Percentage			95.00%
Business Acquisition, Loss Sharing Agreement Losses Up To Threshold To Be Reimbursed Percentage			80.00%
Forrest Sherer Insurance [Domain]
Business Acquisition [Line Items]
Assets					13,000,000	$ 15,800,000
Insurance Services Revenue					7,600,000	8,300,000
Goodwill							$ 5.1
Operating Income (Loss)					$ 168,000	$ 554,000