Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Maximum annual medical cost inflation after retirement for Company's share of retiree medical benefits cost for non Medicare-eligible retirees (as a percent)	5.00%
Pension benefits
Components of net periodic cost
Accumulated benefit obligation	$ 4,480,000,000	$ 4,420,000,000
Company's Pension Plans with an ABO in excess of plan assets
Company's pension plans with ABO in excess of plan assets, aggregate projected benefit obligation	4,270,000,000	84,000,000
Company's pension plans with ABO in excess of plan assets, aggregate accumulated benefit obligation	4,180,000,000	83,000,000
Company's pension plans with ABO in excess of plan assets, aggregate fair value of plan assets	4,090,000,000.00	0
Defined benefit plans' accrued benefit costs related to certain unfunded and non-qualified plans	$ 78,000,000	$ 84,000,000
Postretirement benefits
Defined benefit plan, assumed health care cost trend rates
Weighted average health care cost trend rate	6.80%
Ultimate health care cost trend rate in 2035 and thereafter	4.50%