DOCUMENT AND ENTITY INFORMATION - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2019	Nov. 08, 2019	Mar. 30, 2019
Document and Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Amendment Flag	false
Document Period End Date	Sep. 28, 2019
Entity File Number	0-121
Entity Registrant Name	KULICKE & SOFFA INDUSTRIES INC
Entity Central Index Key	0000056978
Entity Incorporation, State or Country Code	PA
Entity Address, Address Line One	23A Serangoon North Avenue 5
Entity Address, Address Line Two	#01-01
Entity Address, Address Line Three	K&S Corporate Headquarters
Entity Address, City or Town	Singapore
Entity Address, Country	SG
Entity Address, Postal Zip Code	554369
City Area Code	215
Local Phone Number	784-6000
Title of 12(b) Security	Common Stock, Without Par Value
Trading Symbol	KLIC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,444.9
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Tax Identification Number	23-1498399
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--09-28
Entity Common Stock, Shares Outstanding		63,028,039