Derivative Financial Instruments Nature and Amount of Collateral Received From and Posted To Our Derivative Counterparties (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Derivative
Derivative Asset, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset	$ 14.6	$ 12.0
Derivative Liability, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset	176.0	200.7
Cash
Derivative
Cash Collateral from Counterparties	1.4	3.6
Derivative, Collateral, Right to Reclaim Cash	6.8	4.0
Fixed Maturity Securities
Derivative
Carrying Value of Fixed Maturity Securities Posted as Collateral to Counterparties	13.2	8.4
Carrying Value of Fixed Maturity Securities Posted as Collateral to Counterparties	$ 169.2	$ 196.7