| Document and Entity Information | Aug. 10, 2021 |
| Document Information [Line Items] | |
| Entity Registrant Name | BrightSpire Capital, Inc. |
| Document Type | 8-K |
| Document Period End Date | Aug. 10, 2021 |
| Entity Central Index Key | 0001717547 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-38377 |
| Entity Tax Identification Number | 38-4046290 |
| Entity Address, Address Line One | 590 Madison Avenue |
| Entity Address, Address Line Two | 33rd Floor |
| 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 | 547-2631 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A common stock, par value $0.01 per share |
| Trading Symbol | BRSP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
