Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 2,625	$ 91	$ 2,724	$ 483
Other comprehensive income (loss), net of reclassification adjustments:
Foreign currency translation and other losses	28	(17)	5	(30)
Unrealized gains on marketable securities and privately held debt securities	49	6	24	14
Other comprehensive income (loss), before tax	77	(11)	29	(16)
Tax effect	(10)	(1)	(4)	(3)
Other comprehensive income (loss), net	67	(12)	25	(19)
Comprehensive income	$ 2,692	$ 79	$ 2,749	$ 464