Offsetting of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Offsetting Assets and Liabilities [Line Items]
Collateral received	$ 2.9	$ 23.6
Gross amounts not offset in the balance sheet	0.0	0.0
Aggregate fair value of all derivative instruments with credit-risk-related contingent features that are in a liability position	471.5	1,600.0
Collateral deposited with derivative counterparties for derivatives instruments with credit-risk-related contingent features that are in a liability position	425.7	1,400.0
Net maximum amount of termination payments that could have been required	45.8	158.8
Net Investment Hedges
Offsetting Assets and Liabilities [Line Items]
Collateral received	166.3
Gross amounts not offset in the balance sheet	$ 194.2
Cash collateral received from derivative counterparties and not offset against derivative assets		140.6
Cash collateral deposited with derivative counterparties not offset against derivative liabilities		$ 36.4