Long-Duration Insurance Contracts - Undiscounted and Discounted Expected Gross Premiums and Expected Future Benefits and Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Whole life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	$ 547.3	$ 524.0
Expected future benefits and expenses, undiscounted	1,340.4	1,272.9
Expected future gross premiums, discounted	364.1	350.5
Expected future benefits and expenses, discounted	631.9	617.4
Term life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	692.2	712.1
Expected future benefits and expenses, undiscounted	735.9	736.2
Expected future gross premiums, discounted	456.7	464.2
Expected future benefits and expenses, discounted	429.8	433.2
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	453.1	497.8
Expected future benefits and expenses, undiscounted	1,531.5	1,639.0
Expected future gross premiums, discounted	256.3	279.3
Expected future benefits and expenses, discounted	763.3	782.8
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	75.9	73.6
Expected future benefits and expenses, undiscounted	337.8	307.2
Expected future gross premiums, discounted	56.0	54.7
Expected future benefits and expenses, discounted	118.1	114.3
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	1,613.0	1,595.3
Expected future benefits and expenses, undiscounted	674.0	684.6
Expected future gross premiums, discounted	1,160.1	1,165.4
Expected future benefits and expenses, discounted	462.7	482.8
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	0.0	0.0
Expected future benefits and expenses, undiscounted	144.6	150.7
Expected future gross premiums, discounted	0.0	0.0
Expected future benefits and expenses, discounted	$ 103.0	$ 107.3