Schedule IV Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Life insurance in force
Direct Amount	$ 46,536.6	$ 37,107.3	$ 40,422.9
Ceded to Other Companies	11,578.7	10,012.3	9,597.7
Assumed from Other Companies	0.0	0.0	0.0
Net Amount	$ 34,957.9	$ 27,095.0	$ 30,825.2
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Premiums
Direct Amount	$ 1,258.7	$ 1,188.8	$ 1,097.6
Ceded to Other Companies	58.3	70.9	76.3
Assumed from Other Companies	28.0	28.1	35.8
Net Amount	$ 1,228.4	$ 1,146.0	$ 1,057.1
Percentage of Amount Assumed to Net	2.30%	2.50%	3.40%
Property & Casualty
Premiums
Direct Amount	$ 806.8	$ 743.9	$ 653.0
Ceded to Other Companies	20.9	20.5	18.1
Assumed from Other Companies	16.7	13.1	10.7
Net Amount	$ 802.6	$ 736.5	$ 645.6
Percentage of Amount Assumed to Net	2.10%	1.80%	1.70%
Life & Retirement
Premiums
Direct Amount	$ 165.3	$ 161.2	$ 166.5
Ceded to Other Companies	6.7	6.6	14.8
Assumed from Other Companies	0.0	0.0	0.0
Net Amount	$ 158.6	$ 154.6	$ 151.7
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Supplemental & Group Benefits
Premiums
Direct Amount	$ 286.6	$ 283.7	$ 278.1
Ceded to Other Companies	30.7	43.8	43.4
Assumed from Other Companies	11.3	15.0	25.1
Net Amount	$ 267.2	$ 254.9	$ 259.8
Percentage of Amount Assumed to Net	4.20%	5.90%	9.70%