Retirement-Related Benefits - Contributions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Retirement-Related Benefits
Contributions by employer - Noncash	$ 156	$ 129
Total plan contributions	154	170
U.S. and Non-U.S. nonpension postretirement benefit plans
Retirement-Related Benefits
Total plan contributions	120	106
Non-U.S. DB plans and multi-employer plans
Retirement-Related Benefits
Total plan contributions	35	64
Nonpension Postretirement Plans | Non-U.S. DB plans
Retirement-Related Benefits
Contributions by employer - Noncash	$ 105	$ 150