Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Jan. 31, 2014
Jul. 31, 2013
Document And Entity Information [Abstract]    
Document Type 10-K  
Amendment Flag false  
Document Period End Date Jan. 31, 2014  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus FY  
Trading Symbol AMBA  
Entity Registrant Name AMBARELLA INC  
Entity Central Index Key 0001280263  
Current Fiscal Year End Date --01-31  
Entity Well-known Seasoned Issuer No  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding 28,748,513  
Entity Public Float   $ 344