Long-Duration Insurance Contracts - Reconciliation of LFPB to Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	$ 1,463.3	$ 1,611.5
Whole life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	253.5	278.8
Term life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	135.3	144.1
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	663.2	740.8
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	49.6	54.6
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	173.5	191.8
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	85.6	96.0
Limited-pay whole life DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	6.9	6.2
SPIA (life contingent) DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	1.3	1.5
Reconciling items
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	$ 94.4	$ 97.7