Retirement-Related Benefits - Contributions (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Retirement-Related Benefits
Total plan contributions	$ 144	$ 124
Trust for Benefit of Employees
Retirement-Related Benefits
Contributions by employer - noncash	413	390
U.S. nonpension postretirement benefit plan
Retirement-Related Benefits
Total plan contributions	127	104
Non-U.S. DB plans and multi-employer plans
Retirement-Related Benefits
Total plan contributions	$ 17	$ 20