| Document And Entity Information | Apr. 09, 2020 |
| Document Information [Line Items] | |
| Entity, Registrant Name | RETAIL OPPORTUNITY INVESTMENTS CORP. |
| Document, Type | 8-K |
| Document, Period End Date | Apr. 9, 2020 |
| 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 |
| City Area Code | 858 |
| Local Phone Number | 677-0900 |
| Entity, Address, Postal Zip Code | 92130 |
| 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 |
| Trading Symbol | ROIC |
| Security Exchange Name | NASDAQ |
| Amendment Flag | false |
| Entity, Central Index Key | 0001407623 |
| RETAIL OPPORTUNITY INVESTMENTS PARTNERSHIP, LP | |
| Document Information [Line Items] | |
| Entity, Registrant Name | RETAIL OPPORTUNITY INVESTMENTS PARTNERSHIP, LP |
| Entity, Central Index Key | 0001577230 |
