Loans - Schedule of Recorded Investment in Impaired Loans (Details) $ in Millions	Mar. 31, 2020 USD ($)
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	$ 5.9
Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	1.4
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	4.4
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.1
Business Assets Pledged as Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	3.8
Business Assets Pledged as Collateral [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.3
Business Assets Pledged as Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	3.5
Business Assets Pledged as Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.0
Real Property Pledged as Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	1.6
Real Property Pledged as Collateral [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	1.0
Real Property Pledged as Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.5
Real Property Pledged as Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.1
Other Property [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.5
Other Property [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.1
Other Property [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	0.4
Other Property [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Collateral dependent borrowings	$ 0.0