Document And Entity Information - shares	6 Months Ended
	Jun. 27, 2020	Jul. 28, 2020
Document Information [Line Items]
Entity Central Index Key	0000021535
Entity Registrant Name	COHU INC
Amendment Flag	false
Current Fiscal Year End Date	--12-26
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2020
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 27, 2020
Document Transition Report	false
Entity File Number	001-04298
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	95-1934119
Entity Address, Address Line One	12367 Crosthwaite Circle
Entity Address, City or Town	Poway
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92064-6817
City Area Code	858
Local Phone Number	848-8100
Title of 12(b) Security	Common Stock, $1.00 par value
Trading Symbol	COHU
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		41,862,920