v3.19.3.a.u2
Cover page - shares
3 Months Ended
Dec. 31, 2019
Jan. 31, 2020
Cover page.    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Dec. 31, 2019  
Document Transition Report false  
Entity File Number 001-35231  
Entity Registrant Name MITEK SYSTEMS, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 87-0418827  
Entity Address, Address Line One 600 B Street, Suite 100  
Entity Address, City or Town San Diego,  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92101  
City Area Code 619  
Local Phone Number 269-6800  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol MITK  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   40,901,147
Amendment Flag false  
Current Fiscal Year End Date --09-30  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2020  
Entity Central Index Key 0000807863