Retirement Benefits (Schedule of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Pension Plans
Weighted-average assumptions used to determine net periodic benefit costs:
Discount rate	5.10%	2.80%	2.40%
Rate of compensation increase	4.30%	3.50%	3.30%
Expected return on plan assets	8.10%	8.10%	6.80%
Weighted-average assumptions used to determine benefit obligation as of December 31:
Discount rate	4.80%	5.10%	2.80%
Rate of compensation increase	4.30%	4.30%	3.50%
Retiree Health Benefit Plans
Weighted-average assumptions used to determine net periodic benefit costs:
Discount rate	5.20%	3.00%	2.60%
Expected return on plan assets	7.30%	7.30%	5.00%
Weighted-average assumptions used to determine benefit obligation as of December 31:
Discount rate	5.00%	5.20%	3.00%