Business Combinations Estimated Fair Values Of Assets Acquired And Liabilities Assumed (Details) - USD ($)		3 Months Ended	12 Months Ended
	Sep. 08, 2016	Sep. 30, 2017	Dec. 31, 2017	Aug. 14, 2015
OldNationalBankBranches [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			$ 2,700,000	$ 279,468,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans				(152,397,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment				4,422,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount				14,274,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				6,216,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets				1,174,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				457,951,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits				453,647,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities				507,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				457,951,000
Business Combination, Acquisition Related Costs			$ 1,400,000
Finite-Lived Intangible Asset, Useful Life			10 years
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Securities Sold Under Agreements to Repurchase				3,797,000
First Clover Leaf [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$ 59,320,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Securities	(109,174,000)
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	(438,265,000)
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Allowance For Loan Losses	0
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Repossessed Assets	(1,987,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment	11,581,000
Goodwill, Acquired During Period	19,143,000	$ 19,143,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	4,660,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets	26,849,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	670,979,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	536,686,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities	4,177,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	582,508,000
Finite-Lived Intangible Asset, Useful Life			10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	88,471,000
Aggregate Total Of Cash Paid In Business Combination	22,545,000
Business Acquisition, Equity Interest Issued or Issuable	65,926,000
Business Combination, Value of Total Consideration Paid	88,471,000
Business Acquisition, Transaction Costs			$ 3,308,000
Business Acquisition, YTD Transaction Costs			1,967,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Securities Sold Under Agreements to Repurchase	23,263,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, FHLB Advances	15,113,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Subordinated Debentures	(3,269,000)
Acquired Book Value [Member] | OldNationalBankBranches [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				279,468,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans			(156,000,000)	(155,774,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment				4,547,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets				1,433,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				441,222,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits			$ 453,000,000	452,810,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities				507,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				457,114,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Securities Sold Under Agreements to Repurchase				3,797,000
Acquired Book Value [Member] | First Clover Leaf [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	59,320,000
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Securities	(109,911,000)
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	(448,668,000)
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Allowance For Loan Losses	(6,928,000)
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Repossessed Assets	(2,741,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment	9,618,000
Goodwill, Acquired During Period	11,385,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	99,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets	23,974,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	658,788,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	534,692,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities	2,103,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	579,058,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	79,730,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Securities Sold Under Agreements to Repurchase	23,263,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, FHLB Advances	15,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Subordinated Debentures	(4,000,000)
Fair Value Adjustments [Member] | OldNationalBankBranches [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans				3,377,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment				(125,000)
Business Acquisition, Goodwill, Expected Tax Deductible Amount				14,274,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				6,216,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets				(259,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				16,729,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits				837,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				$ 837,000
Fair Value Adjustments [Member] | First Clover Leaf [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	0
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Securities	(737,000)
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	(10,403,000)
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed Allowance For Loan Losses	(6,928,000)
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Repossessed Assets	(754,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Premises And Equipment	1,963,000
Goodwill, Acquired During Period	7,758,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	4,561,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Assets	2,875,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	12,191,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	1,994,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Liabilities	2,074,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	3,450,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	8,741,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed, Securities Sold Under Agreements to Repurchase	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, FHLB Advances	113,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Subordinated Debentures	(731,000)
Fair Value Adjustments, Accretable portion [Member] | First Clover Leaf [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets and Liabilities Assumed, Loans	$ (8,400,000)