v3.8.0.1
Document And Entity Information - USD ($)
$ in Billions
12 Months Ended
Dec. 31, 2017
Feb. 16, 2018
Jun. 30, 2017
Document Information [Line Items]      
Entity Registrant Name RETAIL OPPORTUNITY INVESTMENTS CORP    
Trading Symbol roic    
Document Type 10-K    
Current Fiscal Year End Date --12-31    
Entity Common Stock, Shares Outstanding   112,420,425  
Entity Public Float     $ 2.1
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 Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Retail Opportunity Investments Partnership L.P.      
Document Information [Line Items]      
Entity Registrant Name Retail Opportunity Investments Partnerships L.P.    
Document Type 10-K    
Amendment Flag false    
Entity Central Index Key 0001577230    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Non-accelerated Filer    
Entity Well-known Seasoned Issuer No    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY