Stockholders' Equity (Details 2) (USD $)	1 Months Ended			9 Months Ended		1 Months Ended			3 Months Ended		9 Months Ended		1 Months Ended				3 Months Ended		9 Months Ended		1 Months Ended			3 Months Ended		9 Months Ended
	May 31, 2011	Dec. 31, 2010	Aug. 31, 2009	Sep. 30, 2011	Aug. 17, 2009	Feb. 28, 2011 Starwood Property Trust, Inc. Equity Plan	Jul. 31, 2010 Starwood Property Trust, Inc. Equity Plan	Aug. 31, 2009 Starwood Property Trust, Inc. Equity Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Equity Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Equity Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Equity Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Equity Plan	May 31, 2011 Starwood Property Trust, Inc. Manager Equity Plan	Mar. 31, 2011 Starwood Property Trust, Inc. Manager Equity Plan	Dec. 31, 2010 Starwood Property Trust, Inc. Manager Equity Plan	Aug. 31, 2009 Starwood Property Trust, Inc. Manager Equity Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Manager Equity Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Manager Equity Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Manager Equity Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Manager Equity Plan	Aug. 31, 2011 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Aug. 31, 2010 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Aug. 31, 2009 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Sep. 30, 2011 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Sep. 30, 2010 Starwood Property Trust, Inc. Non-Executive Director Stock Plan
Equity Incentive Plans
Number of shares of common stock reserved for issuance (in shares)									3,112,500		3,112,500													100,000		100,000
Number of directors receiving grants of restricted shares																						$ 4	$ 4			$ 4
Awards granted (in shares)				22,590		11,082		5,000			11,082				1,075,000	1,037,500					2,877	1,000	2,200			11,508
Awards granted, fair value						$ 250,000		$ 100,000							$ 21,800,000	$ 20,800,000					$ 200,000	$ 75,000	$ 175,000
Award vesting period						ratably in quarterly installments over three years		ratably in quarterly installments over three years							ratably in quarterly installments over three years	ratably in quarterly installments over three years					one annual installment on the first anniversary of the grant	one annual installment on the first anniversary of the grant	three annual installments on each of the first, second, and third anniversaries of the grant date
Expenses related to the grant									$ 21,000	$ 0	$ 50,000	$ 16,000					$ 2,900,000	$ 1,700,000	$ 10,300,000	$ 4,600,000				$ 48,000	$ 30,000	$ 114,000	$ 52,000
Awards vesting each quarter (in shares)																86,458
Stock-based compensation (in shares)							1,250
Number of unvested units forfeited (in shares)							3,750
Proceeds from public offering of common stock (in shares)	22,000,000	23,000,000	47,575,000										9,021
Stock issuance price (in dollars per share)	$ 21.67	$ 19.73			$ 20								$ 22.08
Non-Vested Share and Share Equivalents activity
Beginning Balance (in shares)				1,690,809															1,680,208							10,601
Granted (in shares)				22,590		11,082		5,000			11,082				1,075,000	1,037,500					2,877	1,000	2,200			11,508
Vested (in shares)				(537,827)					(924)		(2,771)			(89,583)			(176,041)		(528,123)							(6,933)
Forfeited (in shares)							3,750
Balance at the end of period (in shares)		1,690,809		1,175,572					8,311		8,311				1,680,208		1,152,085		1,152,085					15,176		15,176
Vesting Schedule
2011 (remainder of) (in shares)				176,966					923		923						176,043		176,043
2012 (in shares)				624,338					3,694		3,694						617,709		617,709					2,935		2,935
2013 (in shares)				374,268					3,694		3,694						358,333		358,333					12,241		12,241
Total (in shares)		1,690,809		1,175,572					8,311		8,311				1,680,208		1,152,085		1,152,085					15,176		15,176