Stockholders' Equity (Details 2) (USD $)	3 Months Ended	9 Months Ended			1 Months Ended	3 Months Ended					1 Months Ended						3 Months Ended		0 Months Ended	1 Months Ended			0 Months Ended	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013 item	Sep. 30, 2013 Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan	Sep. 30, 2013 Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan Chief financial officer and/or compliance officer	Feb. 28, 2011 Starwood Property Trust, Inc. Equity Plan Restricted stock	Sep. 30, 2013 Starwood Property Trust, Inc. Equity Plan Restricted stock	Mar. 31, 2013 Starwood Property Trust, Inc. Equity Plan Restricted stock	Sep. 30, 2012 Starwood Property Trust, Inc. Equity Plan Restricted stock	Mar. 31, 2012 Starwood Property Trust, Inc. Equity Plan Restricted stock	Dec. 31, 2012 Starwood Property Trust, Inc. Equity Plan Restricted stock	Mar. 31, 2013 Starwood Property Trust, Inc. Manager Equity Plan	May 31, 2012 Starwood Property Trust, Inc. Manager Equity Plan	Oct. 31, 2012 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	May 31, 2012 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	Dec. 31, 2010 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	Aug. 31, 2009 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	Sep. 30, 2013 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	Sep. 30, 2012 Starwood Property Trust, Inc. Manager Equity Plan Restricted stock units	Sep. 04, 2013 Starwood Property Trust, Inc. Non-Executive Director Stock Plan person	Aug. 31, 2012 Starwood Property Trust, Inc. Non-Executive Director Stock Plan person	Aug. 31, 2011 Starwood Property Trust, Inc. Non-Executive Director Stock Plan person	Sep. 30, 2013 Starwood Property Trust, Inc. Non-Executive Director Stock Plan	Sep. 04, 2013 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Aug. 31, 2012 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Aug. 31, 2011 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Sep. 30, 2013 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Sep. 30, 2012 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Sep. 30, 2013 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Sep. 30, 2012 Starwood Property Trust, Inc. Non-Executive Director Stock Plan Restricted stock	Sep. 30, 2013 Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan - as Amended
Equity Incentive Plans
Number of shares of common stock reserved for issuance			3,112,500	50,000																		100,000								6,000,000
Number of equity incentive plans		3
Number of directors receiving grants of restricted stock																			4	4	4
Awards granted per director (in shares)																							2,807	2,201	2,877
Awards granted, fair value					$ 250,000		$ 694,000		$ 368,000				$ 19,900,000		$ 21,800,000	$ 20,800,000							$ 281,000	$ 200,000	$ 200,000
Award vesting period					3 years		3 years		3 years				3 years		3 years	3 years							1 year	1 year	1 year
Expenses related to the grant						$ 98,000		$ 52,000									$ 3,900,000	$ 4,100,000								$ 47,000	$ 87,000	$ 147,000	$ 216,000
Vested to date (in shares)						4,048		1,965									162,501	178,542
Awards vesting annually (in shares)										5,000
Awards vesting each quarter (in shares)									12,500				72,917		89,583	86,458
Manager incentive fee paid in stock (in shares)											13,188	70,220
Manager incentive fee paid in stock, price per share											$ 27.83	$ 19.76
Non-Vested Share and Share Equivalents activity
Beginning Balance (in shares)	876,486					32,265											835,417									8,804
Granted (in shares)	11,228				11,082		25,000		17,500				875,000	30,000	1,075,000	1,037,500										11,228
Vested (in shares)	(175,353)					(4,048)											(162,501)									(8,804)
Balance at the end of period (in shares)	712,361	712,361				28,217											672,916									11,228		11,228
Vesting Schedule
2013 (remainder of) (in shares)	168,216	168,216				5,715											162,501
2014 (in shares)	317,063	317,063				14,168											291,667									11,228		11,228
2015 (in shares)	227,082	227,082				8,334											218,748
Total (in shares)	712,361	712,361				28,217											672,916									11,228		11,228