Long-Duration Insurance Contracts - Amounts Recognized in the Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	$ 62.1	$ 60.4	$ 183.2	$ 179.1
Interest expense	18.4	18.6	55.4	56.0
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	7.4	7.1	21.8	21.5
Interest expense	3.3	3.1	9.7	9.4
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	12.1	12.4	35.8	35.2
Interest expense	1.6	1.5	4.7	4.4
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	6.8	7.2	20.7	21.9
Interest expense	10.1	10.5	30.7	31.6
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	1.9	1.9	5.3	5.3
Interest expense	0.8	0.8	2.4	2.3
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	33.4	31.3	98.9	93.4
Interest expense	1.6	1.7	5.0	5.2
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Gross premiums or assessments	0.5	0.5	0.7	1.8
Interest expense	$ 1.0	$ 1.0	$ 2.9	$ 3.1