Long-Duration Insurance Contracts - Market Risk Benefits Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Market Risk Benefit [Roll Forward]
Balance, beginning of period	$ (6.8)	$ (3.9)
Balance, beginning of period, before effects of changes in the instrument-specific credit risk	(7.4)	(4.5)
Change in MRB (after-tax)	1.4	(2.3)
Balance, end of period	(6.0)	(6.8)
Effect of changes in the instrument-specific credit risk	0.8	0.5
Balance, end of period	(5.2)	(6.3)
Net amount at risk	$ 19.4	$ 16.6
Weighted-average attained age of contract holders	63 years	62 years