Document And Entity Information (USD $)	3 Months Ended
	Sep. 25, 2011
Entity Registrant Name	INTERNATIONAL RECTIFIER CORP /DE/
Entity Central Index Key	0000316793
Current Fiscal Year End Date	--06-24
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Filer Category	Large Accelerated Filer
Entity Public Float	$ 2,042,788,060
Entity Common Stock, Shares Outstanding	69,046,377
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 25, 2011