Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of level 3 invested assets in total investment portfolio	8.60%		8.60%
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net investment gains (losses) included in net income related to financial assets	$ (0.3)	$ (0.4)	$ 4.6	$ (0.1)
Net investment gains (losses) included in net income related to financial liabilities	$ 1.2	$ (6.6)	$ (4.4)	$ (7.6)