Acquisitions and FDIC Indemnification Asset (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Assets	$ 2,968,048,000	$ 3,000,668,000
Goodwill	34,355,000	34,355,000
Loans and Leases Receivable, Net of Loans with Deteriorated Credit Quality, Covered	3,600,000	$ 4,300,000
First National Bank Of Danville [Member]
Business Acquisition [Line Items]
Reimbursements from the FDIC	19,400,000
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%