| Document and Entity Information | Mar. 24, 2020 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001332551 |
| Document Type | 8-K |
| Document Period End Date | Mar. 24, 2020 |
| Entity Registrant Name | Exantas Capital Corp. |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 1-32733 |
| Entity Tax Identification Number | 20-2287134 |
| Entity Address, Address Line One | 717 Fifth Avenue |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10022 |
| City Area Code | 212 |
| Local Phone Number | 621-3210 |
| 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] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, $0.001 par value |
| Trading Symbol | XAN |
| Security Exchange Name | NYSE |
| Eight Point Six Two Five Percentage Series C Cumulative Redeemable Preferred Stocks [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 8.625% Fixed-to-Floating Series C Cumulative Redeemable Preferred Stock |
| Trading Symbol | XANPrC |
| Security Exchange Name | NYSE |
