Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 01, 2023	Jun. 30, 2022
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40923
Entity Registrant Name	FRANKLIN BSP REALTY TRUST, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	46-1406086
Entity Address, Address Line One	1345 Avenue of the Americas
Entity Address, Address Line Two	Suite 32A
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10105
City Area Code	(212)
Local Phone Number	588-6770
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,123.9
Entity Common Stock, Shares Outstanding		82,885,961
Documents Incorporated by Reference	Portions of the definitive proxy statement to be filed by Franklin BSP Realty Trust, Inc. with the Securities and Exchange Commission pursuant to Regulation 14A relating to the registrant’s Annual Meeting of Stockholders to be held on May 31, 2023 will be incorporated by reference in this Form 10-K in response to Items 10, 11, 12, 13 and 14 of Part III. The definitive proxy statement will be filed with the SEC not later than 120 days after the registrant’s fiscal year ended December 31, 2022.
Entity Central Index Key	0001562528
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Stock
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	FBRT
Security Exchange Name	NYSE
Series E Preferred Stock
Title of 12(b) Security	7.50% Series E Cumulative Redeemable Preferred Stock, par value $0.01 per share
Trading Symbol	FBRT PRE
Security Exchange Name	NYSE