v3.8.0.1
Document and Entity Information - shares
3 Months Ended
Dec. 31, 2017
Jan. 29, 2018
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Dec. 31, 2017  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1  
Trading Symbol MITK  
Entity Registrant Name MITEK SYSTEMS INC  
Entity Central Index Key 0000807863  
Current Fiscal Year End Date --09-30  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   34,902,816