Retirement-Related Benefits - All Retirement Plans Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Retirement-Related Benefits
Defined benefit and contribution pension plans - cost	$ 281	$ 478
Nonpension postretirement plans - cost	32	33
Total	$ 314	510
Year-to-year percent change, defined benefit and contribution pension plans cost (as a percent)	(41.10%)
Year-to-year percent change, nonpension postretirement plans cost (as a percent)	(1.60%)
Year-to-year percent change, total (as a percent)	(38.50%)
U.S. | Pension Plans
Retirement-Related Benefits
Defined benefit and contribution pension plans - cost	$ 90	$ 149