v3.19.1
Document And Entity Information - shares
3 Months Ended
Mar. 30, 2019
Apr. 23, 2019
Document Information [Line Items]    
Entity Registrant Name COHU INC  
Entity Central Index Key 0000021535  
Trading Symbol cohu  
Current Fiscal Year End Date --12-28  
Entity Filer Category Accelerated Filer  
Entity Current Reporting Status Yes  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Common Stock, Shares Outstanding (in shares)   41,016,916
Document Type 10-Q  
Document Period End Date Mar. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Amendment Flag false