Document and Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Jan. 01, 2012	Feb. 23, 2012	Jul. 03, 2011
Document and Entity Information
Entity Registrant Name	POWER ONE INC
Entity Central Index Key	0001042825
Document Type	10-K
Document Period End Date	Jan. 01, 2012
Amendment Flag	false
Current Fiscal Year End Date	--01-01
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 833
Entity Common Stock, Shares Outstanding		121,941,782
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY