Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Continuing Operations:
Basic - Income attributable to STWD common stockholders	$ 102,358	$ 26,657
Less: Income attributable to participating shares	(899)	(708)
Basic earnings	101,459	25,949
Continuing Operations:
Basic - Income attributable to STWD common stockholders	102,358	26,657
Less: Income attributable to participating shares	(899)	(708)
Diluted earnings	$ 101,459	$ 25,949
Number of Shares:
Basic - Average shares outstanding	258,997	236,556
Effect of dilutive securities - Convertible Notes (in shares)	3,220
Effect of dilutive securities - Contingently Issuable Shares (in shares)	121	121
Effect of dilutive securities — Unvested non-participating shares	103	82
Diluted - Average shares outstanding	262,441	236,759
Basic:
Basic (in dollars per share)	$ 0.39	$ 0.11
Diluted:
Diluted (in dollars per share)	$ 0.39	$ 0.11