v3.8.0.1
Document And Entity Information - shares
3 Months Ended
Mar. 31, 2018
Apr. 20, 2018
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   112,720,459
Amendment Flag false  
Entity Central Index Key 0001407623  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
Entity Filer Category Large Accelerated Filer  
Entity Well-known Seasoned Issuer Yes  
Document Period End Date Mar. 31, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1  
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