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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Loans Held for Investment - Schedule of Loans by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Loans and Leases Receivable
Loans and Leases Receivable, Deferred Income	$ (8.3)	$ (11.1)
Accounts Receivable, Allowance for Credit Loss	(191.4)	(204.1)	$ (227.7)	$ (220.1)
Loans and Leases Receivable, Collateral for Secured Borrowings	15,201.6	17,844.9
Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	8,144.4	9,263.2
Real Estate Construction Financing Receivable [Member]
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	837.2	1,244.6
Residential Mortgage [Member]
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	2,108.8	2,191.6
Agricultural Real Estate Financing Receivable [Member]
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	629.0	701.1
Real Estate Financing Receivable [Member]
Loans and Leases Receivable
Accounts Receivable, Allowance for Credit Loss	(131.2)	(139.4)	(160.1)	(138.7)
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	11,719.4	13,400.5
Indirect consumer
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	477.5	725.0
Other consumer
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	131.5	134.0
Credit card consumer
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	0.0	77.6
Total consumer loans
Loans and Leases Receivable
Accounts Receivable, Allowance for Credit Loss	(11.2)	(16.8)	(13.0)	(23.3)
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	609.0	936.6
Commercial Portfolio Segment [Member]
Loans and Leases Receivable
Accounts Receivable, Allowance for Credit Loss	(36.9)	(38.9)	(50.2)	(54.9)
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	2,359.6	2,829.4
Agricultural Financing Receivable [Member]
Loans and Leases Receivable
Accounts Receivable, Allowance for Credit Loss	(12.1)	(9.0)	$ (4.4)	$ (3.2)
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	520.2	687.9
Other, including overdrafts
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	1.7	1.6
Loans held for investment
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	15,209.9	17,856.0
Residential Real Estate
Loans and Leases Receivable
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	$ 2,108.8	$ 2,191.6