v3.19.2
Cover Page - shares
9 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Cover page.    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2019  
Document Transition Report false  
Entity File Number 000-30205  
Entity Registrant Name CABOT MICROELECTRONICS CORPORATION  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 36-4324765  
Entity Address, Address Line One 870 North Commons Drive  
Entity Address, City or Town Aurora  
Entity Address, State or Province IL  
Entity Address, Postal Zip Code 60504  
City Area Code 630  
Local Phone Number 375-6631  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol CCMP  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   29,036,385
Entity Central Index Key 0001102934  
Current Fiscal Year End Date --09-30  
Amendment Flag false  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3