Secured Financing Agreements (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended	9 Months Ended			9 Months Ended						9 Months Ended				0 Months Ended	1 Months Ended	9 Months Ended					0 Months Ended	9 Months Ended			0 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Apr. 19, 2013 LNR item	Sep. 30, 2013 Wells Fargo II	Sep. 30, 2013 Wells Fargo II Minimum	Sep. 30, 2013 Wells Fargo II Maximum	Sep. 30, 2013 Wells Fargo III	Sep. 30, 2013 Wells Fargo IV	Sep. 30, 2013 Goldman III	Sep. 30, 2013 Citibank	Sep. 30, 2013 Citibank Minimum	Sep. 30, 2013 Citibank Maximum	Sep. 30, 2013 Onewest Bank	Sep. 30, 2013 Borrowing Base	Sep. 30, 2013 Conduit I	Sep. 30, 2013 Conduit II	Apr. 19, 2013 Senior credit facility LNR	Apr. 30, 2013 Term Loan	Sep. 30, 2013 Term Loan	Sep. 30, 2013 Term Loan BB+/Ba2(S&P/Moody's)	Sep. 30, 2013 Term Loan LIBOR	Sep. 30, 2013 SMF I Conduit I LNR	Apr. 19, 2013 SMF I Conduit I LNR	Apr. 19, 2013 SMF I Conduit I LIBOR LNR	Sep. 30, 2013 SMF I Conduit I LIBOR LNR	Sep. 30, 2013 SMF II Conduit II LNR	Apr. 19, 2013 SMF II Conduit II LNR	Apr. 19, 2013 SMF II Conduit II LIBOR LNR	Sep. 30, 2013 SMF II Conduit II LIBOR LNR	Sep. 30, 2013 Starwood Property Mortgage, LLC Amended Wells RMBS Repurchase Agreement
Debt Instrument:
Pricing rate, basis							LIBOR			LIBOR	LIBOR	LIBOR	LIBOR			LIBOR	LIBOR					LIBOR		one-month LIBOR			one-month LIBOR	one-month LIBOR			one-month LIBOR	one-month LIBOR
Pricing margin (as a percent)								1.75%	6.00%	1.90%	2.75%	3.70%		1.75%	3.75%	3.00%	3.25%					2.75%		2.75%			2.20%	2.20%			2.10%	2.10%
Pledged Asset Carrying Value							$ 842,044,000			$ 289,830,000	$ 210,949,000	$ 210,125,000	$ 158,643,000			$ 124,822,000	$ 591,916,000					$ 1,726,171,000			$ 75,234,000				$ 203,887,000
Maximum Facility Size							550,000,000			175,000,000	154,935,000	149,989,000	125,000,000			84,012,000	250,000,000					298,500,000			250,000,000	250,000,000			150,000,000	150,000,000
Carrying Value	1,312,044,000		1,312,044,000		1,305,812,000		246,810,000			72,719,000	154,935,000	149,989,000	100,952,000			84,012,000						297,794,000			55,395,000				149,438,000
Maximum borrowing capacity																	250,000,000					300,000,000
Maturity period																						7 years
Borrowing cost (as a percent)																						3.84%
Fees to obtain facility																					7,100,000
Maximum liability guaranteed (as a percent)																										25.00%				20.00%
Repayment of outstanding balance plus accrued interest			2,674,437,000	1,164,373,000																268,900,000
Floor interest rate (as a percent)																						0.75%
Extended term																																	180 days
Number of repurchase facilities assumed						2
Debt instrument , credit rating																							BB+/Ba2(S&P/Moody's)
Discount amortization			(1,211,000)	(669,000)																		706,000
Repayment of secured financings
2013 (remainder of)	239,106,000		239,106,000													32,400,000		55,400,000	149,400,000
2014	589,295,000		589,295,000
2015	192,599,000		192,599,000
2016	3,000,000		3,000,000
2017 and thereafter	288,750,000		288,750,000
Total	1,312,750,000		1,312,750,000
Capitalized financing costs, net of amortization	11,600,000		11,600,000		7,800,000
Amortization of financing costs included in interest expense	$ 2,100,000	$ 1,500,000	$ 7,000,000	$ 3,900,000