Loans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($) loan	Mar. 01, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 261,450,000			$ 317,760,000
Carrying amount of loans acquired in business combination	$ 1,975,147,000	$ 1,549,909,000
Number of loans modified as troubled debt restructuring | loan	0	0
Troubled debt restructuring, additional lending amount	$ 0	$ 0
Number of loans that subsequently default after modification | loan	0	0	1
Recorded investment of loans that subsequently default after modification			$ 95,000
Mortgage loans in process of foreclosure	$ 202,000	$ 169,000
Loans Acquired with Deteriorated Credit Quality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Decrease in allowance for loans that subsequently default after modification	107,000	0	54,000
Loans Purchased
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, reversal	2,000	$ 54,000	0
Troubled Debt Restructuring that Subsequently Defaulted
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs due to troubled debt restructurings			91,000
Decrease in allowance for loans that subsequently default after modification			$ (90,000)
River Valley Bancorp
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans				317,760,000
Carrying amount of loans acquired in business combination	269,014,000			328,431,000
Fair value discount of loans acquired in business combination	$ 7,564,000			$ 10,671,000