Catastrophe Reinsurance - Catastrophe Reinsurance Premiums (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Liability for Catastrophe Claims [Line Items]
Ceded earned premiums	$ 17.3	$ 33.1	$ 32.7
Catastrophe Reinsurance
Liability for Catastrophe Claims [Line Items]
Ceded earned premiums	1.3	16.4	16.3
Operating Segments \| Specialty Property & Casualty Insurance \| Catastrophe Reinsurance
Liability for Catastrophe Claims [Line Items]
Ceded earned premiums	1.2	6.5	6.1
Operating Segments \| Life Insurance \| Catastrophe Reinsurance
Liability for Catastrophe Claims [Line Items]
Ceded earned premiums	0.1	0.3	0.7
Non-Core Operations \| Catastrophe Reinsurance
Liability for Catastrophe Claims [Line Items]
Ceded earned premiums	$ 0.0	$ 9.6	$ 9.5

Amount of earned premiums ceded to other entities.

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+ Details