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Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Financing Receivable, Accrued Interest, Writeoff | $ (2.7) | $ 1.5
Commercial Real Estate Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 8,869.2 | 8,528.6
Real Estate Construction Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 1,826.5 | 1,944.4
Residential Mortgage [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 2,244.3 | 2,188.3
Agricultural Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 716.8 | 794.9
Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 13,656.8 | 13,456.2
Agricultural Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 769.4 | 708.3
Commercial Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 2,906.8 | 2,882.6
Loans held for investment |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 18,292.1 | 18,114.8
Indirect consumer |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 740.9 | 829.7
Other consumer |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 141.6 | 152.9
Collateral |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 52.6 | 39.1
Collateral | Commercial Real Estate Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 26.6 | 17.5
Collateral | Real Estate Construction Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 17.0 | 3.2
Collateral | Agricultural Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 1.2 | 6.0
Collateral | Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 45.3 | 27.2
Collateral | Agricultural Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.7 | 7.3
Collateral | Residential Real Estate |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.5 | 0.5
Collateral | Commercial Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 6.6 | 4.6
Business Assets Pledged as Collateral | Collateral |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 5.2 | 7.1
Business Assets Pledged as Collateral | Collateral | Commercial Real Estate Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 1.7
Business Assets Pledged as Collateral | Collateral | Real Estate Construction Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Business Assets Pledged as Collateral | Collateral | Agricultural Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.2
Business Assets Pledged as Collateral | Collateral | Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 1.9
Business Assets Pledged as Collateral | Collateral | Agricultural Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.7 | 2.1
Business Assets Pledged as Collateral | Collateral | Residential Real Estate |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Business Assets Pledged as Collateral | Collateral | Commercial Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 4.5 | 3.1
Real Property Pledged as Collateral | Collateral |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 46.7 | 32.0
Real Property Pledged as Collateral | Collateral | Commercial Real Estate Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 26.6 | 15.8
Real Property Pledged as Collateral | Collateral | Real Estate Construction Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 17.0 | 3.2
Real Property Pledged as Collateral | Collateral | Agricultural Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 1.2 | 5.8
Real Property Pledged as Collateral | Collateral | Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 45.3 | 25.3
Real Property Pledged as Collateral | Collateral | Agricultural Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 5.2
Real Property Pledged as Collateral | Collateral | Residential Real Estate |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.5 | 0.5
Real Property Pledged as Collateral | Collateral | Commercial Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 1.4 | 1.5
Other Property | Collateral |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.7 | 0.0
Other Property | Collateral | Commercial Real Estate Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Real Estate Construction Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Agricultural Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Real Estate Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Agricultural Financing Receivable [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Residential Real Estate |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | 0.0 | 0.0
Other Property | Collateral | Commercial Portfolio Segment [Member] |  |
Loans and Leases Receivable Recorded Investment, Impaired [Line Items] |  |
Loans and Leases Receivable, Collateral for Secured Borrowings | $ 0.7 | $ 0.0

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