Business Combinations Pro Forma Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
OldNationalBankBranches [Member]
Business Acquisition [Line Items]
Business Acquisitions Pro Forma Net Interest Income		$ 66,680
Business Acquisitions Pro Forma Provision For Loan Losses		1,483
Business Acquisitions Pro Forma Non-Interest Income		26,001
Business Acquisitions Pro Forma Non-Interest Expense		59,944
Business Acquisitions Pro Forma Income before Income Taxes		31,254
Business Acquisitions Pro Forma, Income Tax Expense		11,207
Business Acquisition, Pro Forma Net Income (Loss)		20,047
Pro Forma Earnings Per Share
Business Acquisitions Pro Forma, Dividends On Preferred Shares		2,200
Business Acquisitions Pro Forma, Net Income Available To Common Stockholders		$ 17,847
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 2,300
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 2,190
Weighted Average Basic Shares Outstanding, Pro Forma		7,775,490
Pro Forma Weighted Average Shares Outstanding, Diluted		9,137,689
First Clover Leaf [Member]
Business Acquisition [Line Items]
Business Acquisitions Pro Forma Net Interest Income	$ 85,004	$ 76,619
Business Acquisitions Pro Forma Provision For Loan Losses	3,556	1,548
Business Acquisitions Pro Forma Non-Interest Income	29,118	23,217
Business Acquisitions Pro Forma Non-Interest Expense	73,997	66,864
Business Acquisitions Pro Forma Income before Income Taxes	36,569	31,424
Business Acquisitions Pro Forma, Income Tax Expense	12,910	10,671
Business Acquisition, Pro Forma Net Income (Loss)	23,659	20,753
Pro Forma Earnings Per Share
Business Acquisitions Pro Forma, Dividends On Preferred Shares	825	1,650
Business Acquisitions Pro Forma, Net Income Available To Common Stockholders	$ 22,834	$ 19,103
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 2,250	$ 2,390
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 2,220	$ 2,220
Weighted Average Basic Shares Outstanding, Pro Forma	10,149,099	7,985,089
Pro Forma Weighted Average Shares Outstanding, Diluted	10,663,710	9,347,288