Cover Page - USD ($)	12 Months Ended
	Dec. 28, 2019	Feb. 07, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Entity Interactive Data Current	Yes
Document Period End Date	Dec. 28, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	INTEVAC INC
Entity Central Index Key	0001001902
Current Fiscal Year End Date	--12-28
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Trading Symbol	IVAC
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	0-26946
Entity Tax Identification Number	94-3125814
Entity Address, Address Line One	3560 Bassett Street
Entity Address, City or Town	Santa Clara
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95054
City Area Code	408
Local Phone Number	986-9888
Entity Small Business	true
Title of 12(b) Security	Common Stock
Entity Common Stock, Shares Outstanding		23,559,479
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 108,615,756
Entity Voluntary Filers	No