Document and Entity Information - USD ($)
12 Months Ended
Jan. 31, 2019
Mar. 18, 2019
Jul. 31, 2018
Document and Entity Information      
Entity Registrant Name SPLUNK INC    
Entity Central Index Key 0001353283    
Document Type 10-K    
Document Period End Date Jan. 31, 2019    
Amendment Flag false    
Current Fiscal Year End Date --01-31    
Entity Emerging Growth Company false    
Entity Small Business false    
Entity Shell Company false    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 10,152,428,666
Entity Common Stock, Shares Outstanding   150,074,503  
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY