Schedule IV Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Life insurance in force
Gross Amount	$ 38,564.6	$ 21,032.6	$ 20,460.8
Ceded to Other Companies	9,330.9	4,693.5	4,793.6
Assumed from Other Companies	0.0	0.0	0.0
Net Amount	$ 29,233.7	$ 16,339.1	$ 15,667.2
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Premiums
Gross Amount	$ 1,048.0	$ 913.2	$ 949.6
Ceded to Other Companies	72.0	33.3	28.8
Assumed from Other Companies	53.0	9.7	9.9
Net Amount	$ 1,029.0	$ 889.6	$ 930.7
Percentage of Amount Assumed to Net	5.20%	1.10%	1.10%
Property & Casualty
Premiums
Gross Amount	$ 614.7	$ 623.0	$ 653.0
Ceded to Other Companies	15.0	15.3	12.8
Assumed from Other Companies	8.5	9.7	9.9
Net Amount	$ 608.2	$ 617.4	$ 650.1
Percentage of Amount Assumed to Net	1.40%	1.60%	1.50%
Life & Retirement
Premiums
Gross Amount	$ 160.2	$ 160.3	$ 161.1
Ceded to Other Companies	14.9	16.1	14.1
Assumed from Other Companies	0.0	0.0	0.0
Net Amount	$ 145.3	$ 144.2	$ 147.0
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Supplemental & Group Benefits
Premiums
Gross Amount	$ 273.1	$ 129.9	$ 135.5
Ceded to Other Companies	42.1	1.9	1.9
Assumed from Other Companies	44.5	0.0	0.0
Net Amount	$ 275.5	$ 128.0	$ 133.6
Percentage of Amount Assumed to Net	16.20%	0.00%	0.00%