Loans (Schedule of Aging of Recorded Investment in Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	$ 2,098,726	[1]	$ 2,001,415	[2]
Loans Past Due	12,903	[1]	9,435	[2]
Loans Not Past Due	2,085,823	[1]	1,991,980	[2]
Accrued interest included in recorded investment	9,013		8,011
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	9,099		11,048
Loans Past Due	27		757
Loans Not Past Due	9,072		10,291
Receivables Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income			262,809
Loans Past Due			4,740
Loans Not Past Due			258,069
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	476,167	[1]	458,538	[2]
Loans Past Due	2,565		101
Loans Not Past Due	473,602		458,437
Commercial and Industrial Loans and Leases | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	945		1,656
Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	900,937	[1]	858,030	[2]
Loans Past Due	2,252		1,860
Loans Not Past Due	898,685		856,170
Commercial Real Estate Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	6,492		7,688
Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	331,482	[1]	306,946	[2]
Loans Past Due	361		744
Loans Not Past Due	331,121		306,202
Agricultural Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	768		706
Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	146,393	[1]	134,032	[2]
Loans Past Due	741		796
Loans Not Past Due	145,652		133,236
Home Equity Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	0		0
Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	63,816	[1]	60,099	[2]
Loans Past Due	1,416		407
Loans Not Past Due	62,400		59,692
Consumer Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	0		53
Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	179,931	[1]	183,770	[2]
Loans Past Due	5,568		5,527
Loans Not Past Due	174,363		178,243
Residential Mortgage Loans | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, net of deferred income	894		945
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	8,850	[1]	5,965	[2]
30-59 Days Past Due | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	0		130
30-59 Days Past Due | Receivables Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due			2,752
30-59 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	2,264		20
30-59 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	1,452		1,509
30-59 Days Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	133		84
30-59 Days Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	569		707
30-59 Days Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	1,019		175
30-59 Days Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	3,413		3,470
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	1,753	[1]	1,489	[2]
60-89 Days Past Due | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	0		0
60-89 Days Past Due | Receivables Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due			862
60-89 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	301		4
60-89 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	0		21
60-89 Days Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	0		50
60-89 Days Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	34		16
60-89 Days Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	33		147
60-89 Days Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	1,385		1,251
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	2,300	[1]	1,981	[2]
90 Days or More Past Due | Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	27		627
90 Days or More Past Due | Receivables Acquired with Deteriorated Credit Quality | River Valley Bancorp
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due			1,126
90 Days or More Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	0		77
90 Days or More Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	800		330
90 Days or More Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	228		610
90 Days or More Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	138		73
90 Days or More Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	364		85
90 Days or More Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Past Due	$ 770		$ 806

[1] Total recorded investment in loans includes $9,013 in accrued interest.

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