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, 2018			730
Beginning balance at Jan. 31, 2018		$ 10,376	$ 1	$ 9,752	$ (12)	$ 635
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting changes	[1]	(17)			(7)	(10)
Common stock issued (in shares)			11
Common stock issued		384		384
Shares issued related to business combinations, net (in shares)			10
Shares issued related to business combinations, net		1,565		1,565
Settlement of convertible notes and warrants (in shares)			6
Settlement of convertible notes and warrants		4		4
Stock-based expenses		603		603
Other comprehensive loss, net of tax		(31)			(31)
Net income		643				643
Ending balance (in shares) at Jul. 31, 2018			757
Ending balance at Jul. 31, 2018		13,527	$ 1	12,308	(50)	1,268
Beginning balance (in shares) at Apr. 30, 2018			734
Beginning balance at Apr. 30, 2018		11,060	$ 1	10,123	(33)	969
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (in shares)			7
Common stock issued		269		269
Shares issued related to business combinations, net (in shares)			10
Shares issued related to business combinations, net		1,565		1,565
Settlement of convertible notes and warrants (in shares)			6
Settlement of convertible notes and warrants		0		0
Stock-based expenses		351		351
Other comprehensive loss, net of tax		(17)			(17)
Net income		299				299
Ending balance (in shares) at Jul. 31, 2018			757
Ending balance at Jul. 31, 2018		13,527	$ 1	12,308	(50)	1,268
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)		3	10
Common stock issued		$ 366		366
Stock-based expenses		731		731
Other comprehensive loss, net of tax		(19)			(19)
Net income		483				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

[1] Reflects the cumulative effect adjustments upon the adoption of Accounting Standards Update ("ASU") 2016-01, "Financial Instruments - Overall (Subtopic 825-10)" ("ASU 2016-01") and ASU 2016-16, "Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory."