Reinsurance and Catastrophes - Effects of Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Direct Amount
Net premiums written and contract deposits, Direct Amount	$ 1,734.5	$ 1,650.9	$ 1,583.6
Net premiums and contract charges earned, Direct Amount	1,258.7	1,188.8	1,097.7
Benefits, claims and settlement expenses, Direct Amount	744.1	748.3	803.6
Ceded to Other Companies
Net premiums written and contract deposits, Ceded to Other Companies	59.0	72.0	67.9
Net premiums and contract charges earned, Ceded to Other Companies	58.3	70.9	76.3
Benefits, claims and settlement expenses, Ceded to Other Companies	48.1	43.0	45.7
Assumed from Other Companies
Net premiums written and contract deposits, Assumed from Other Companies	34.2	28.8	36.9
Net premiums and contract charges earned, Assumed from Other Companies	28.0	28.1	35.7
Benefits, claims and settlement expenses, Assumed from Other Companies	15.5	39.7	11.2
Net Amount
Net premiums written and contract deposits, Net Amount	1,709.7	1,607.7	1,552.6
Net premiums and contract charges earned, Net Amount	1,228.4	1,146.0	1,057.1
Benefits, claims and settlement expenses	$ 711.5	$ 745.0	$ 769.1