Retirement Benefits - Schedule of Amounts Recognized on Balance Sheets Related to Qualified Defined Benefit Pension Plans and Retiree Medical and Life Insurance Plans (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liabilities	$ (3,915)	$ (4,791)
Qualified Defined  Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Other noncurrent assets	30	6
Accrued pension liabilities	(3,915)	(4,791)
Net (unfunded) funded status of the plans	(3,885)	(4,785)
Retiree Medical and Life Insurance Plans
Defined Benefit Plan Disclosure [Line Items]
Other noncurrent assets	666	564
Accrued pension liabilities	0	0
Net (unfunded) funded status of the plans	$ 666	$ 564