Retirement-Related Benefits - Contributions - (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Retirement-Related Benefits
Contributions by employer - Noncash	$ 192	$ 156
Total plan contributions	117	154
Non-U.S. DB plans and multi-employer plans
Retirement-Related Benefits
Total plan contributions	7	35
Nonpension Postretirement Plans | U.S. nonpension postretirement benefit plan
Retirement-Related Benefits
Contributions by employer - Noncash	109	105
Total plan contributions	$ 109	$ 120