| Cover | Dec. 07, 2020 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 7, 2020 |
| Entity Registrant Name | AG Mortgage Investment Trust, Inc. |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-35151 |
| Entity Tax Identification Number | 27-5254382 |
| Entity Address, Address Line One | 245 Park Avenue |
| Entity Address, Address Line Two | 26th floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10167 |
| City Area Code | 212 |
| Local Phone Number | 692-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001514281 |
| Common Stock | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock, $0.01 par value per share |
| Trading Symbol | MITT |
| Security Exchange Name | NYSE |
| Series Cumulative Reedmable Preferred Stock | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 8.25% Series A Cumulative Redeemable Preferred Stock |
| Trading Symbol | MITT PrA |
| Security Exchange Name | NYSE |
| Series B Cumulative Reedmable Preferred Stock | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 8.00% Series B Cumulative Redeemable Preferred Stock |
| Trading Symbol | MITT PrB |
| Security Exchange Name | NYSE |
| Series C Fixed to Floating Rate Cumulative Redeemable Preferred | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 8.000% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock |
| Trading Symbol | MITT PrC |
| Security Exchange Name | NYSE |
