Document And Entity Information	3 Months Ended
	Apr. 28, 2012	May 25, 2012
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 28, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
Entity Registrant Name	COST PLUS INC/CA/
Entity Central Index Key	0000798955
Current Fiscal Year End Date	--02-02
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		22,515,752