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 income (loss), net	(7)			(7)
Net income (loss)	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 income (loss), net	(16)
Net income (loss)	374
Ending balance (in shares) at Oct. 31, 2019		886
Ending balance at Oct. 31, 2019	33,279	$ 1	31,243	(74)	2,109
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 income (loss), net	(12)			(12)
Net income (loss)	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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		4
Common stock issued	88		88
Stock-based expenses	543		543
Shares issued related to business combinations (in shares)		102
Shares issued related to business combinations	15,588		15,588
Other comprehensive income (loss), net	3			3
Net income (loss)	(109)				(109)
Ending balance (in shares) at Oct. 31, 2019		886
Ending balance at Oct. 31, 2019	33,279	$ 1	31,243	(74)	2,109
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 income (loss), net	(42)			(42)
Net income (loss)	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 income (loss), net	9
Net income (loss)	3,805
Ending balance (in shares) at Oct. 31, 2020		914
Ending balance at Oct. 31, 2020	40,310	$ 1	34,727	(84)	5,666
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 income (loss), net	67			67
Net income (loss)	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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)		6
Common stock issued	239		239
Stock-based expenses	566		566
Other comprehensive income (loss), net	(16)			(16)
Net income (loss)	1,081				1,081
Ending balance (in shares) at Oct. 31, 2020		914
Ending balance at Oct. 31, 2020	$ 40,310	$ 1	$ 34,727	$ (84)	$ 5,666