Earnings per Share - Reconciliation of Net Income and Number of Shares used in Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Basic Earnings
Income attributable to STWD common stockholders	$ 112,255	$ 154,332
Less: Income attributable to participating shares not already deducted as non-controlling interests	(2,265)	(2,576)
Basic earnings	109,990	151,756
Diluted Earnings
Income attributable to STWD common stockholders	112,255	154,332
Less: Income attributable to participating shares not already deducted as non-controlling interests	(2,265)	(2,576)
Add: Undistributed earnings to participating shares	0	68
Less: Undistributed earnings reallocated to participating shares	0	(65)
Diluted earnings	$ 109,990	$ 158,764
Number of Shares:
Basic - Average shares outstanding (in shares)	335,059	311,827
Effect of dilutive securities - Contingently issuable shares (in shares)	252	469
Effect of dilutive securities - Unvested non-participating shares (in shares)	145	200
Diluted - Average shares outstanding (in shares)	335,456	330,840
Earnings Per Share Attributable to STWD Common Stockholders:
Basic (in dollars per share)	$ 0.33	$ 0.49
Diluted (in dollars per share)	$ 0.33	$ 0.48
Unamortized discount—Convertible Notes
Diluted Earnings
Add: Interest expense on Convertible Notes	$ 0	$ 7,005
Number of Shares:
Effect of dilutive securities - Convertible Notes (in shares)	0	18,344