Retirement-Related Benefits - Contributions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Retirement-Related Benefits
Total plan contributions	$ 208	$ 233
Trust for Benefit of Employees
Retirement-Related Benefits
Contributions by employer - Noncash	600	537
U.S. nonpension postretirement benefit plan
Retirement-Related Benefits
Total plan contributions	155	188
Non-U.S. DB plans and multi-employer plans
Retirement-Related Benefits
Total plan contributions	$ 53	$ 45