Business Combinations Pro Forma Information (Details) - First BancTrust [Member] - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Business Acquisitions Pro Forma Net Interest Income	$ 30,087,000	$ 27,373,000	$ 86,813,000	$ 83,289,000
Business Acquisitions Pro Forma Provision For Loan Losses	2,551,000	1,679,000	5,683,000	5,546,000
Business Acquisitions Pro Forma Non-Interest Income	7,919,000	8,544,000	24,879,000	25,758,000
Business Acquisitions Pro Forma Non-Interest Expense	24,490,000	24,271,000	68,144,000	72,157,000
Business Acquisitions Pro Forma Income before Income Taxes	10,965,000	9,967,000	37,865,000	31,344,000
Business Acquisitions Pro Forma, Income Tax Expense	2,731,000	3,315,000	9,356,000	10,147,000
Business Acquisition, Pro Forma Net Income (Loss)	$ 8,234,000	$ 6,652,000	$ 28,509,000	$ 21,197,000
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 540	$ 470	$ 1,940	$ 1,500
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 540	$ 470	$ 1,940	$ 1,500
Weighted Average Basic Shares Outstanding, Pro Forma	15,290,539	14,172,574	14,704,888	14,142,813
Pro Forma Weighted Average Shares Outstanding, Diluted	15,308,218	14,179,709	14,721,708	14,150,476
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 10,660,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ 3,366,000