Long-Duration Insurance Contracts - Reconciliation of LFPB to Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	$ 1,635.7	$ 1,622.8
Whole life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	279.7	275.2
Term life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	138.4	131.8
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	749.9	746.6
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	53.7	52.1
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	203.0	203.5
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	97.2	97.3
Limited-pay whole life DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	5.5	5.2
SPIA (life contingent) DPL
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	1.4	1.5
Reconciling items
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net liability for future policy benefits	$ 106.9	$ 109.6