XML 13 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document and Entity Information - shares
 9 Months Ended
Oct. 31, 2018
Dec. 03, 2018
Document Information [Abstract]    
Entity Registrant Name MongoDB, Inc.  
Entity Central Index Key 0001441816  
Current Fiscal Year End Date --01-31  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Small Business false  
Document Type 10-Q  
Document Period End Date Oct. 31, 2018  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Class A Common Stock    
Entity Common Stock, Shares Outstanding   35,408,828
Class B Common Stock    
Entity Common Stock, Shares Outstanding   18,194,724