| Cover | Aug. 26, 2022 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 26, 2022 |
| Entity File Number | 001-36844 |
| Entity Registrant Name | GREAT AJAX CORP. |
| Entity Central Index Key | 0001614806 |
| Entity Tax Identification Number | 46-5211870 |
| Entity Incorporation, State or Country Code | MD |
| Entity Address, Address Line One | 13190 SW 68th Parkway |
| Entity Address, Address Line Two | Suite 110 |
| Entity Address, City or Town | Tigard |
| Entity Address, State or Province | OR |
| Entity Address, Postal Zip Code | 97223 |
| City Area Code | 503 |
| Local Phone Number | 505-5670 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Title of 12(b) Security | Common stock, par value $0.01 per share |
| Trading Symbol | AJX |
| Security Exchange Name | NYSE |
| Convertible Senior Notes [Member] | |
| Title of 12(b) Security | 7.25% Convertible Senior Notes due 2024 |
| Trading Symbol | AJXA |
| Security Exchange Name | NYSE |
