Employee Benefits - Amounts Recognized on Balance Sheet and Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Amounts recognized in the balance sheets
Non-current liabilities	$ (11,997)	$ (13,189)
Pension
Amounts recognized in the balance sheets
Current liabilities	(38)	(42)
Non-current liabilities	(1,078)	(1,555)
Total	(1,116)	(1,597)
Amounts recognized in Accumulated other comprehensive loss (pre-tax)
Prior service cost (benefit)	523	635
Total	523	635
Health Care and Life
Amounts recognized in the balance sheets
Current liabilities	(643)	(685)
Non-current liabilities	(9,430)	(10,304)
Total	(10,073)	(10,989)
Amounts recognized in Accumulated other comprehensive loss (pre-tax)
Prior service cost (benefit)	(833)	(962)
Total	$ (833)	$ (962)