Employee and Agent Benefits - ABO in Excess of Plan Assets (Details) - Pension benefits - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Information for Defined Benefit Plans With an Accumulated Benefit Obligation in Excess of Plan Assets
Projected benefit obligation for defined benefit plans with an accumulated benefit obligation in excess of plan assets	$ 3,209.4	$ 4,183.7
Accumulated benefit obligation for defined benefit plans with an accumulated benefit obligation in excess of plan assets	3,209.4	4,149.3
Fair value of plan assets for defined benefit plans with an accumulated benefit obligation in excess of plan assets	$ 2,726.3	$ 3,550.1