Employee Benefits - Amounts Recognized on Balance Sheet and Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Amounts recognized in the balance sheets
Non-current liabilities	$ (12,974)	$ (15,410)
Pension
Amounts recognized in the balance sheets
Non-current assets	4	376
Current liabilities	(48)	(55)
Non-current liabilities	(1,586)	(401)
Total	(1,630)	(80)
Amounts recognized in Accumulated other comprehensive loss (pre-tax)
Prior service cost (benefit)	747	402
Total	747	402
Health Care and Life
Amounts recognized in the balance sheets
Non-current assets	0	0
Current liabilities	(718)	(748)
Non-current liabilities	(9,939)	(13,381)
Total	(10,657)	(14,129)
Amounts recognized in Accumulated other comprehensive loss (pre-tax)
Prior service cost (benefit)	(1,355)	(1,889)
Total	$ (1,355)	$ (1,889)