Condensed Consolidated Statements of Stockholders’ Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Jan. 31, 2019		770
Beginning balance at Jan. 31, 2019	$ 15,605	$ 1	$ 13,927	$ (58)	$ 1,735
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		5
Common stock issued	113		113
Stock-based expenses	343		343
Other comprehensive loss, net of tax	(7)			(7)
Net income	392				392
Ending balance (in shares) at Apr. 30, 2019		775
Ending balance at Apr. 30, 2019	16,446	$ 1	14,383	(65)	2,127
Beginning balance (in shares) at Jan. 31, 2019		770
Beginning balance at Jan. 31, 2019	15,605	$ 1	13,927	(58)	1,735
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss, net of tax	(19)
Net income	483
Ending balance (in shares) at Jul. 31, 2019		780
Ending balance at Jul. 31, 2019	17,166	$ 1	15,024	(77)	2,218
Beginning balance (in shares) at Apr. 30, 2019		775
Beginning balance at Apr. 30, 2019	16,446	$ 1	14,383	(65)	2,127
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		5
Common stock issued	253		253
Stock-based expenses	388		388
Other comprehensive loss, net of tax	(12)			(12)
Net income	91				91
Ending balance (in shares) at Jul. 31, 2019		780
Ending balance at Jul. 31, 2019	17,166	$ 1	15,024	(77)	2,218
Beginning balance (in shares) at Jan. 31, 2020		893
Beginning balance at Jan. 31, 2020	33,885	$ 1	32,116	(93)	1,861
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		6
Common stock issued	119		119
Stock-based expenses	504		504
Other comprehensive loss, net of tax	(42)			(42)
Net income	99				99
Ending balance (in shares) at Apr. 30, 2020		899
Ending balance at Apr. 30, 2020	34,565	$ 1	32,739	(135)	1,960
Beginning balance (in shares) at Jan. 31, 2020		893
Beginning balance at Jan. 31, 2020	33,885	$ 1	32,116	(93)	1,861
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss, net of tax	25
Net income	2,724
Ending balance (in shares) at Jul. 31, 2020		908
Ending balance at Jul. 31, 2020	38,440	$ 1	33,922	(68)	4,585
Beginning balance (in shares) at Apr. 30, 2020		899
Beginning balance at Apr. 30, 2020	34,565	$ 1	32,739	(135)	1,960
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		9
Common stock issued	605		605
Stock-based expenses	578		578
Other comprehensive loss, net of tax	67			67
Net income	2,625				2,625
Ending balance (in shares) at Jul. 31, 2020		908
Ending balance at Jul. 31, 2020	$ 38,440	$ 1	$ 33,922	$ (68)	$ 4,585