Long-Duration Insurance Contracts - Amounts Recognized in the Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	$ 60.1	$ 59.4
Interest expense	18.5	18.8
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	7.0	7.0
Interest expense	3.2	3.1
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	11.5	11.7
Interest expense	1.5	1.4
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	6.9	7.4
Interest expense	10.3	10.6
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	1.8	1.8
Interest expense	0.8	0.8
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	32.7	30.9
Interest expense	1.7	1.8
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	0.2	0.6
Interest expense	$ 1.0	$ 1.1