Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) segment quarter	Dec. 31, 2019 USD ($)	Dec. 31, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Number of segments | segment	3
Periods used to calculate general component for allowance for loan losses (in quarters) | quarter	20
Required cash on deposit at Federal Reserve	$ 10,967		$ 11,659
Assets	3,144,360		2,955,994		$ 2,373,701
Liabilities and Equity	3,144,360		2,955,994
ASU 2016-02 | Scenario, Forecast
Property, Plant and Equipment [Line Items]
Assets		$ 6,000
Liabilities and Equity		$ 6,000
River Valley Bancorp
Property, Plant and Equipment [Line Items]
Fair value of mortgage servicing rights	$ 547		$ 611
Assets				$ 516,300
Minimum
Property, Plant and Equipment [Line Items]
Finite-lived intangible asset, useful life	6 years
Maximum
Property, Plant and Equipment [Line Items]
Finite-lived intangible asset, useful life	10 years
Buildings and related components | Minimum
Property, Plant and Equipment [Line Items]
Premises, furniture, and equipment, useful life	10 years
Buildings and related components | Maximum
Property, Plant and Equipment [Line Items]
Premises, furniture, and equipment, useful life	40 years
Furniture, fixtures and equipment | Minimum
Property, Plant and Equipment [Line Items]
Premises, furniture, and equipment, useful life	3 years
Furniture, fixtures and equipment | Maximum
Property, Plant and Equipment [Line Items]
Premises, furniture, and equipment, useful life	10 years