Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,081	$ (109)	$ 3,805	$ 374
Other comprehensive income (loss), net of reclassification adjustments:
Foreign currency translation and other losses	(6)	(1)	(1)	(31)
Unrealized gains (losses) on marketable securities and privately held debt securities	(11)	4	13	18
Other comprehensive income (loss), before tax	(17)	3	12	(13)
Tax effect	1	0	(3)	(3)
Other comprehensive income (loss), net	(16)	3	9	(16)
Comprehensive income (loss)	$ 1,065	$ (106)	$ 3,814	$ 358