| Cover | Oct. 07, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 7, 2021 |
| Entity Registrant Name | Ellington Residential Mortgage REIT |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-35896 |
| Entity Tax Identification Number | 46-0687599 |
| Entity Address, Address Line One | 53 Forest Avenue |
| Entity Address, City or Town | Old Greenwich |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06870 |
| City Area Code | 203 |
| Local Phone Number | 698-1200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares of Beneficial Interest, $0.01 par value per share |
| Trading Symbol | EARN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001560672 |
| Amendment Flag | false |
