Basis of Accounting and Consolidation Basis of Accounting and Consolidation (Acquisitions)	Sep. 08, 2016 USD ($) $ / shares shares	Sep. 30, 2017 $ / shares	Dec. 31, 2016 $ / shares
Agreement And Plan Of Merger FCLB [Abstract]
Common stock, par value (in dollars per share) | $ / shares		$ 4	$ 4
First Clover Leaf [Member]
Branch Purchase and Assumption Agreement ONB [Abstract]
Fair value of loans	$ 438,265,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	$ 536,686,000
Agreement And Plan Of Merger FCLB [Abstract]
Percent Of Acquiree Outstanding Stock Being Acquired In Merger	1.00
Percentage of business acquisition consideration paid in cash	25.00%
Right To Receive Value of Cash Option | $ / shares	$ 12.87
Aggregate Total Of Cash Paid In Business Combination	$ 22,545,000
Portion of Business Acquisition Consideration Paid In Common Stock	75.00%
Right To Receive Value Of Share Option | shares	0.495
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	2,600,616