Retirement-Related Benefits - Schedule of Contribution Expense Related to Defined Contribution Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2025	Jan. 31, 2024	Jan. 31, 2023
Contribution expense from retirement plans [Line Items]
Total contribution expense for defined contribution plans	$ 1,829	$ 1,613	$ 1,565
U.S.
Contribution expense from retirement plans [Line Items]
Total contribution expense for defined contribution plans	1,751	1,528	1,491
International
Contribution expense from retirement plans [Line Items]
Total contribution expense for defined contribution plans	$ 78	$ 85	$ 74