Revenues - Disaggregation of Revenue (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	[1],[2]	$ 3,392	$ 2,701	$ 9,679	$ 7,675
Americas
Disaggregation of Revenue [Line Items]
Total revenues		2,425	1,942	6,864	5,575
Europe
Disaggregation of Revenue [Line Items]
Total revenues		641	499	1,876	1,374
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenues		$ 326	$ 260	$ 939	$ 726
Untied States | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Concentration risk percentage		96.00%	96.00%	96.00%	96.00%
Subscription and support
Disaggregation of Revenue [Line Items]
Total revenues	[1],[2]	$ 3,168	$ 2,506	$ 9,038	$ 7,098
Sales Cloud
Disaggregation of Revenue [Line Items]
Total revenues		1,020	921	2,989	2,642
Service Cloud
Disaggregation of Revenue [Line Items]
Total revenues		917	738	2,657	2,094
Salesforce Platform and Other
Disaggregation of Revenue [Line Items]
Total revenues		742	491	2,029	1,378
Marketing and Commerce Cloud
Disaggregation of Revenue [Line Items]
Total revenues		$ 489	$ 356	$ 1,363	$ 984

[1] Amounts include amortization of intangible assets acquired through business combinations, as follows: Three Months Ended October 31, Nine Months Ended October 31, 2018 2017 2018 2017Cost of revenues$62 $40 $153 $127Marketing and sales67 30 164 91

[2] Amounts include stock-based expense, as follows: Three Months Ended October 31, Nine Months Ended October 31, 2018 2017 2018 2017Cost of revenues$42 $33 $119 $97Research and development81 66 228 197Marketing and sales180 118 474 357General and administrative48 34 133 108