v3.3.1.900
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2015
Feb. 19, 2016
Jun. 30, 2015
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   99,590,468  
Entity Public Float     $ 1,400,000,000
Amendment Flag false    
Entity Central Index Key 0001407623    
Entity Current Reporting Status Yes    
Entity Voluntary Filers Yes    
Entity Filer Category Large Accelerated Filer    
Entity Well-known Seasoned Issuer Yes    
Document Period End Date Dec. 31, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY    
Retail Opportunity Investments Partnership L.P. [Member]      
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