Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Earnings Per Share [Abstract]
Net loss	$ (25,172)	$ 3,708	$ (68,683)	$ (57,107)	$ (21,465)	$ (125,792)
Net loss attributable to noncontrolling interests:
Investment Entities	2,054		823		3,688	827
Net loss attributable to BrightSpire Capital, Inc. common stockholders	(23,118)		(67,860)		(17,777)	(124,965)
Numerator:
Dividends allocated to participating securities (non-vested shares)	(471)		(509)		(940)	(1,050)
Net loss attributable to common stockholders	$ (23,589)		$ (68,369)		$ (18,717)	$ (126,015)
Denominator:
Weighted average shares outstanding - basic (in shares)	127,247,000		127,986,000		127,165,000	127,656,000
Weighted average shares outstanding - diluted (in shares)	127,247,000		127,986,000		127,165,000	127,656,000
Net loss per common share - basic (in dollars per share)	$ (0.19)		$ (0.53)		$ (0.15)	$ (0.99)
Net loss per common share - diluted (in dollars per share)	$ (0.19)		$ (0.53)		$ (0.15)	$ (0.99)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding (in shares)	4,407,095	4,393,650	3,465,443	3,623,715	4,407,095	3,465,443	3,661,351	3,172,185
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding (in shares)	2,945,872	2,932,427	2,547,009	2,705,281	2,945,872	2,547,009	2,742,917	2,787,807
Antidilutive securities excluded from computation of earnings per share (in shares)	2,938,780		2,679,084		2,859,189	2,733,024