Net Income per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Income per Share
Net income attributable to Starwood Property Trust, Inc.	$ 89,715	$ 50,212	$ 214,239	$ 144,861
Net income allocated to participating securities	(310)	(275)	(1,133)	(980)
Numerator for basic and diluted net income per share	$ 89,405	$ 49,937	$ 213,106	$ 143,881
Basic weighted average shares outstanding	171,520,231	116,673,477	156,614,647	107,077,837
Diluted weighted average shares outstanding	172,394,882	117,381,559	157,650,258	107,958,047
Basic income per share	$ 0.52	$ 0.43	$ 1.36	$ 1.34
Diluted income per share	$ 0.52	$ 0.43	$ 1.36	$ 1.34
Unvested restricted stock units and restricted stock awards (in shares)			712,361	478,947
Shares issuable as incentive fee payable to manager			99,601	47,736
Number of anti-dilutive potential common shares excluded from the calculation of diluted income per share			38,800,000