Long-Duration Insurance Contracts - Undiscounted and Discounted Expected Gross Premiums and Expected Future Benefits and Expenses (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	$ 548.0	$ 547.3
Expected future benefits and expenses, undiscounted	1,349.3	1,340.4
Expected future gross premiums, discounted	345.8	364.1
Expected future benefits and expenses, discounted	616.4	631.9
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	700.1	692.2
Expected future benefits and expenses, undiscounted	751.5	735.9
Expected future gross premiums, discounted	454.8	456.7
Expected future benefits and expenses, discounted	437.3	429.8
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	434.4	453.1
Expected future benefits and expenses, undiscounted	1,492.8	1,531.5
Expected future gross premiums, discounted	246.7	256.3
Expected future benefits and expenses, discounted	750.9	763.3
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	75.4	75.9
Expected future benefits and expenses, undiscounted	342.0	337.8
Expected future gross premiums, discounted	55.4	56.0
Expected future benefits and expenses, discounted	119.3	118.1
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Expected future gross premiums, undiscounted	1,635.8	1,613.0
Expected future benefits and expenses, undiscounted	684.5	674.0
Expected future gross premiums, discounted	1,166.9	1,160.1
Expected future benefits and expenses, discounted	464.2	462.7
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	139.7	144.6
Expected future gross premiums, discounted	0.0	0.0
Expected future benefits and expenses, discounted	$ 99.8	$ 103.0

Liability For Future Policy Benefit, Expected Future Policy Benefit, Discounted, Before Reinsurance

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- Definition

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+ References

No definition available.

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- Definition

Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit.

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- Definition

Amount, before effect of reinsurance, of undiscounted balance for expected future gross premium component of liability for future policy benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E

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- Definition

Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.

+ References

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