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	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Basic Earnings
Income attributable to STWD common stockholders	$ 339,213	$ 871,475	$ 447,739
Less: Income attributable to participating shares not already deducted as non-controlling interests	(6,412)	(17,113)	(6,808)
Basic earnings	332,801	854,362	440,931
Diluted Earnings
Income attributable to STWD common stockholders	339,213	871,475	447,739
Less: Income attributable to participating shares not already deducted as non-controlling interests	(6,412)	(17,113)	(6,808)
Add: Undistributed earnings to participating shares	0	11,229	0
Less: Undistributed earnings reallocated to participating shares	0	(10,880)	0
Diluted earnings	$ 332,801	$ 866,343	$ 452,550
Number of Shares:
Basic - Average shares outstanding (in shares)	309,771	305,524	285,942
Effect of dilutive securities - Contingently issuable shares (in shares)	450	386	1,037
Effect of dilutive securities - Unvested non-participating shares (in shares)	286	169	198
Diluted - Average shares outstanding (in shares)	310,507	315,728	296,826
Earnings Per Share Attributable to STWD Common Stockholders:
Basic (in dollars per share)	$ 1.07	$ 2.80	$ 1.54
Diluted (in dollars per share)	$ 1.07	$ 2.74	$ 1.52
Unamortized discount—Convertible Notes
Diluted Earnings
Add: Interest expense on Convertible Notes		$ 11,632	$ 11,619
Number of Shares:
Effect of dilutive securities - Convertible Notes (in shares)		9,649	9,649