Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ 46,789	$ (104,581)	$ (375,584)
Net (income) loss attributable to noncontrolling interests:
Investment Entities	12	1,732	13,924
Operating Partnership	(1,013)	1,803	8,361
Net income (loss) attributable to BrightSpire Capital, Inc. common stockholders	45,788	(101,046)	(353,299)
Numerator:
Net (income) loss allocated to participating securities (non-vested shares)	(1,604)	0	(322)
Net income (loss) attributable to BrightSpire Capital, Inc. common stockholders	$ 44,184	$ (101,046)	$ (353,621)
Denominator:
Weighted average shares of common stock outstanding - basic (in shares)	127,302,000	128,496,000	128,548,000
Weighted average shares of common stock outstanding - diluted (in shares)	129,300,000	128,496,000	128,548,000
Net income (loss) per common share - basic (in dollars per share)	$ 0.35	$ (0.79)	$ (2.75)
Net income (loss) per common share - diluted (in dollars per share)	$ 0.34	$ (0.79)	$ (2.75)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding (in shares)	2,580,691	1,754,094	885,070	1,335,590
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding (in shares)	2,308,691	1,482,094	885,070	1,335,590
Antidilutive securities excluded from computation of earnings per share (in shares)		1,603,486