Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2018
Taxes [Line Items]
Tax expense		$ 442
Accumulated foreign earnings, percent	15.50%
Transition tax on accumulated foreign, percent	8.00%
Accumulated foreign earnings, provisional income tax expense		413
Deferred tax liability	$ 2,000
Operating loss and capital loss carryforwards	38,400
Valuation allowances	8,782		$ 8,588
Unrecognized tax benefits	3,135	$ 1,305	1,817	$ 1,010
Unrecognized tax benefits that would impact effective tax rate	1,700		$ 1,600
Operating loss and capital loss carryforward expiring by 2040 [Member]
Taxes [Line Items]
Operating loss and capital loss carryforwards	$ 26,400