Retirement-Related Benefits - Schedule of Contribution Expense Related to Defined Contribution Plans (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Jan. 31, 2026 |
Jan. 31, 2025 |
Jan. 31, 2024 |
|
| Contribution expense from retirement plans [Line Items] | |||
| Total contribution expense for defined contribution plans | $ 1,896 | $ 1,829 | $ 1,613 |
| U.S. | |||
| Contribution expense from retirement plans [Line Items] | |||
| Total contribution expense for defined contribution plans | 1,810 | 1,751 | 1,528 |
| International | |||
| Contribution expense from retirement plans [Line Items] | |||
| Total contribution expense for defined contribution plans | $ 86 | $ 78 | $ 85 |