Allowance for Credit Losses (Accrued Interest) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Receivables [Abstract]
Loans	$ 184.6	$ 211.7
Debt Securities
Held to Maturity	76.9	58.9
Available for Sale	175.0	173.9
Other Financial Assets	62.2	53.1
Interest Receivable	$ 498.7	$ 497.6
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets