Long-Duration Insurance Contracts - Reconciliation of LFPB to Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	$ 1,655.0	$ 1,761.8
Whole life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	280.0	298.8
Term life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	127.8	130.2
Experience Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	757.3	811.3
Limited Pay Whole Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	53.6	57.4
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	220.4	245.6
Life Contingent SPIA Retirement Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	98.5	104.2
Limited-pay whole life DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	4.5	4.1
SPIA (life contingent) DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	1.4	1.3
Reconciling items
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability for Future Policy Benefit, before Reinsurance	$ 111.5	$ 108.9