Loans (Schedule of Risk Category of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 2,154,502	[1]	$ 2,001,415	[2]
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	488,058	[1]	458,538	[2]
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	929,040	[1]	858,030	[2]
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	337,801	[1]	306,946	[2]
Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	9,117		11,048		$ 7,555
Loans Acquired with Deteriorated Credit Quality | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	988		1,656		1,325
Loans Acquired with Deteriorated Credit Quality | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	6,452		7,688		5,363
Loans Acquired with Deteriorated Credit Quality | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	789		706		$ 0
Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			262,809
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,660,271		1,539,361
Pass | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	462,212		437,353
Pass | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	894,027		814,033
Pass | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	304,032		287,975
Pass | Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	2,604		1,897
Pass | Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			175,915
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	53,226		51,673
Special Mention | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	7,901		10,454
Special Mention | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	18,037		26,549
Special Mention | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	27,288		14,670
Special Mention | Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,647		3,121
Special Mention | Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			11,638
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	41,402		32,480
Substandard | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	17,945		10,731
Substandard | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	16,976		17,448
Substandard | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	6,481		4,301
Substandard | Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	3,978		5,032
Substandard | Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			8,145
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		0
Doubtful | Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			0
Total
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	1,754,899		1,623,514
Total | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	488,058		458,538
Total | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	929,040		858,030
Total | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	337,801		306,946
Total | Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 8,229		10,050
Total | Loans Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income			$ 195,698

[1] Total recorded investment in loans includes $9,483 in accrued interest.

[2] Total recorded investment in loans includes $8,011 in accrued interest.