| Cover Page | Feb. 16, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 16, 2021 |
| Entity Registrant Name | KKR Real Estate Finance Trust Inc. |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-38082 |
| Entity Tax Identification Number | 47-2009094 |
| Entity Address, Address Line One | 30 Hudson Yards, |
| Entity Address, Address Line Two | Suite 7500 |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10001 |
| City Area Code | 212 |
| Local Phone Number | 750-8300 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001631596 |
| Amendment Flag | false |
| Entity Addresses [Line Items] | |
| Entity Address, Address Line One | 30 Hudson Yards, |
| Entity Address, Address Line Two | Suite 7500 |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10001 |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common stock, par value $0.01 per share |
| Trading Symbol | KREF |
| Security Exchange Name | NYSE |
| Former Address | |
| Cover [Abstract] | |
| Entity Address, Address Line One | 9 West 57th Street, |
| Entity Address, Address Line Two | Suite 4200 |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10019 |
| Entity Addresses [Line Items] | |
| Entity Address, Address Line One | 9 West 57th Street, |
| Entity Address, Address Line Two | Suite 4200 |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10019 |
