v3.5.0.2
Document and Entity Information - shares
9 Months Ended
Oct. 31, 2016
Dec. 05, 2016
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Oct. 31, 2016  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q3  
Trading Symbol AMBA  
Entity Registrant Name AMBARELLA INC  
Entity Central Index Key 0001280263  
Current Fiscal Year End Date --01-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   33,112,114