Employee and Agent Benefits - Weighted Average Assumptions (Details)	3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension benefits
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Discount rate: Benefit obligation (as a percent)				5.10%	2.75%
Interest crediting rate - cash balance benefit				5.00%	5.00%
Rate of compensation increase: Benefit obligation (as a percent)				4.53%	4.59%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate: Net periodic benefit cost (as a percent)				2.75%	2.50%	3.25%
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)				5.20%	5.55%	5.60%
Interest crediting rate - cash balance benefit				5.00%	5.00%	5.00%
Pension benefits, Cash balance benefit
Weighted-average assumptions used to determine net periodic benefit cost
Rate of compensation increase: Net periodic benefit cost (as a percent)				4.59%	4.92%	4.95%
Pension benefits, Traditional benefit
Weighted-average assumptions used to determine net periodic benefit cost
Rate of compensation increase: Net periodic benefit cost (as a percent)					2.96%	2.98%
Other postretirement benefits
Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section
Discount rate: Benefit obligation (as a percent)				5.00%	2.50%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate: Net periodic benefit cost (as a percent)		2.95%	2.90%	2.50%	2.10%	2.95%
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)				4.25%	4.25%	4.94%
Assumed Health Care Cost Trend Rates
Health care cost trend rate assumed for next year under age 65 (as a percent)				7.00%	7.00%
Health care cost trend rate assumed for next year age 65 and over (as a percent)				6.00%	6.50%
Rate to which the health care cost trend rate is assumed to decline (the ultimate trend rate) (as a percent)				4.50%	4.50%
Year that the health care cost trend rate reaches the ultimate trend rate under age 65 (calendar year)				2031	2030
Year that the health care cost trend rate reaches the ultimate trend rate age 65 and over (calendar year)				2028	2029
Home office medical and life plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)				4.25%
Agent medical and life plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)				4.25%
Long-term care plans
Weighted-average assumptions used to determine net periodic benefit cost
Subsidy increase cap allowed per calendar year (as a percent)	5.00%
Post-65 medical plans
Weighted-average assumptions used to determine net periodic benefit cost
Expected long-term return on plan assets: Net periodic benefit cost (as a percent)				4.25%