| Cover Page | Jul. 29, 2020 |
| Entity Information [Line Items] | |
| Document Type | 8-K/A |
| Document Period End Date | Jul. 29, 2020 |
| Entity Registrant Name | RETAIL OPPORTUNITY INVESTMENTS CORP |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-33749 |
| Entity Tax Identification Number | 26-0500600 |
| Entity Address, Address Line One | 11250 El Camino Real, Suite 200 |
| Entity Address, City or Town | San Diego, |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92130 |
| City Area Code | 858 |
| Local Phone Number | 677-0900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | ROIC |
| Security Exchange Name | NASDAQ |
| Amendment Flag | true |
| Entity Central Index Key | 0001407623 |
| Retail Opportunity Investments Partnerships L.P. | |
| Entity Information [Line Items] | |
| Entity Registrant Name | RETAIL OPPORTUNITY INVESTMENTS PARTNERSHIP, LP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 333-189057-01 |
| Entity Tax Identification Number | 94-2969738 |
| Entity Central Index Key | 0001577230 |
