Revenues - Disaggregation of Revenue (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 3,006	$ 2,397
Americas
Disaggregation of Revenue [Line Items]
Revenues	2,101	1,765
Europe
Disaggregation of Revenue [Line Items]
Revenues	606	409
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	$ 299	$ 223
Untied States | Geographic Concentration Risk | Revenue
Disaggregation of Revenue [Line Items]
Concentration risk percentage	96.00%	96.00%
Subscription and Support
Disaggregation of Revenue [Line Items]
Revenues	$ 2,810	$ 2,209
Sales Cloud
Disaggregation of Revenue [Line Items]
Revenues	965	830
Service Cloud
Disaggregation of Revenue [Line Items]
Revenues	848	656
Salesforce Platform and Other
Disaggregation of Revenue [Line Items]
Revenues	575	424
Marketing and Commerce Cloud
Disaggregation of Revenue [Line Items]
Revenues	$ 422	$ 299