Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 20, 2017
Document Information [Line Items]
Entity Registrant Name	RETAIL OPPORTUNITY INVESTMENTS CORP
Trading Symbol	ROIC
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		109,730,196
Amendment Flag	false
Entity Central Index Key	0001407623
Entity Filer Category	Large Accelerated Filer
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Retail Opportunity Investments Partnership L.P.
Document Information [Line Items]
Entity Registrant Name	RETAIL OPPORTUNITY INVESTMENTS PARTNERSHIPS L.P.
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001577230
Entity Filer Category	Non-accelerated Filer