Long-Duration Insurance Contracts - Amounts Recognized in the Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	$ 61.1	$ 59.3	$ 121.2	$ 118.7
Interest expense	18.6	18.6	37.1	37.4
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	7.4	7.4	14.4	14.4
Interest expense	3.3	3.2	6.5	6.3
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	12.2	11.1	23.7	22.8
Interest expense	1.6	1.5	3.1	2.9
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	7.0	7.3	13.9	14.7
Interest expense	10.3	10.5	20.6	21.1
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	1.6	1.6	3.4	3.4
Interest expense	0.8	0.7	1.6	1.5
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	32.9	31.2	65.6	62.1
Interest expense	1.6	1.7	3.3	3.5
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	0.0	0.7	0.2	1.3
Interest expense	$ 1.0	$ 1.0	$ 2.0	$ 2.1