Variable Interest Entities (Summary of Unconsolidated Tax Structures) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Variable Interest Entity [Line Items]
Investment Carrying Amount	$ 856.6	$ 876.7
Unfunded Commitments	210.8	227.1
Affordable Housing
Variable Interest Entity [Line Items]
Investment Carrying Amount	640.4	657.0
Unfunded Commitments	210.8	227.1
New Markets
Variable Interest Entity [Line Items]
Investment Carrying Amount	216.2	219.7
Unfunded Commitments	0.0	0.0
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investment Carrying Amount	830.5	849.3
Unfunded Commitments	$ 207.5	$ 221.0