Schedule 4 - Reinsurance Schedule (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Life Insurance in Force
Gross Amount		$ 19,651.3	$ 19,750.8	$ 19,885.1
Ceded to Other Companies		322.5	339.4	354.8
Assumed from Other Companies		123.6	129.9	137.1
Net Amount		$ 19,452.4	$ 19,541.3	$ 19,667.4
Percentage of Amount Assumed to Net		0.60%	0.70%	0.70%
Premiums
Gross Amount		$ 4,238.5	$ 4,532.4	$ 5,229.8
Ceded to Other Companies		33.1	32.7	42.7
Assumed from Other Companies		10.5	29.7	26.3
Net Amount	[1]	$ 4,215.9	$ 4,529.4	$ 5,213.4
Percentage of Amount Assumed to Net		0.20%	0.70%	0.50%
Life Insurance
Premiums
Gross Amount		$ 330.7	$ 322.0	$ 355.8
Ceded to Other Companies		3.1	3.3	3.6
Assumed from Other Companies		0.5	0.5	0.6
Net Amount		$ 328.1	$ 319.2	$ 352.8
Percentage of Amount Assumed to Net		0.20%	0.20%	0.20%
Accident and Health Insurance
Premiums
Gross Amount		$ 34.7	$ 34.7	$ 167.9
Ceded to Other Companies		12.5	11.6	1.1
Assumed from Other Companies		0.0	0.0	1.4
Net Amount		$ 22.2	$ 23.1	$ 168.2
Percentage of Amount Assumed to Net		0.00%	0.00%	0.80%
Property and Liability Insurance
Premiums
Gross Amount		$ 3,873.1	$ 4,175.7	$ 4,706.1
Ceded to Other Companies		17.5	17.8	38.0
Assumed from Other Companies		10.0	29.2	24.3
Net Amount		$ 3,865.6	$ 4,187.1	$ 4,692.4
Percentage of Amount Assumed to Net		0.30%	0.70%	0.50%

[1] 1 Includes a remeasurement loss related to the deferred profit liability within the Life Insurance business of $7.2 million for the year ended December 31, 2024, a remeasurement loss of $19.1 million for the year ended December 31, 2023, and a remeasurement gain of $13.3 million for the year ended December 31, 2022.