Document And Entity Information - USD ($)
12 Months Ended
Jun. 30, 2019
Aug. 22, 2019
Dec. 28, 2018
Document Information [Line Items]      
Entity Registrant Name TWIN DISC INC    
Entity Central Index Key 0000100378    
Trading Symbol twin    
Current Fiscal Year End Date --06-30    
Entity Filer Category Accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer No    
Entity Emerging Growth Company false    
Entity Small Business true    
Entity Common Stock, Shares Outstanding (in shares)   13,332,485  
Entity Public Float     $ 152,303,678
Entity Shell Company false    
Document Type 10-K    
Document Period End Date Jun. 30, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Amendment Flag false    
Title of 12(b) Security Common Stock