Business Combinations Business Combinations Narrative (Details)	Nov. 15, 2018 USD ($) $ / shares shares	May 01, 2018 USD ($) $ / shares shares	Mar. 31, 2019 $ / shares	Dec. 31, 2018 $ / shares
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares			$ 4	$ 4
SCB Bancorp [Member]
Business Acquisition [Line Items]
Percent Of Acquiree Outstanding Stock Being Acquired In Merger	1.00
Par Value Of Outstanding Stock Being Acquired In Merger | $ / shares	$ 7.50
Right To Receive Value of Cash Option | $ / shares	$ 307.93
Aggregate Total Of Cash Paid In Business Combination	$ 19,046,000
Right To Receive Value Of Share Option | shares	8.0228
Dividends, Cash	$ 25,000,000
Total assets acquired	478,629,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	247,561,000
Deposits	347,971,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment	$ 11,068,000
Shares, Issued | shares	1,330,571
First BancTrust [Member]
Business Acquisition [Line Items]
Percent Of Acquiree Outstanding Stock Being Acquired In Merger		1.00
Par Value Of Outstanding Stock Being Acquired In Merger | $ / shares		$ 0.01
Right To Receive Value of Cash Option | $ / shares		$ 5.00
Aggregate Total Of Cash Paid In Business Combination		$ 10,275,000
Right To Receive Value Of Share Option | shares		0.800
Total assets acquired		$ 501,285,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans		363,281,000
Deposits		385,624,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment		9,437,000
Goodwill, Acquired During Period		$ 26,491,000
Shares, Issued | shares		1,643,900
Shares Issued, Price Per Share | $ / shares		$ 37.32
Acquired Book Value [Member] | SCB Bancorp [Member]
Business Acquisition [Line Items]
Total assets acquired	$ 457,324,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	255,429,000
Deposits	348,314,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment	$ 10,115,000
Acquired Book Value [Member] | First BancTrust [Member]
Business Acquisition [Line Items]
Total assets acquired		$ 474,853,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans		371,156,000
Deposits		384,323,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment		$ 10,126,000