Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Assets:
Cash and cash equivalents	$ 536,834		$ 177,671	$ 144,199	$ 114,027
Restricted cash	82,706		3,429
Loans held-for-investment, net	3,790,262		2,914,434
Loans held-for-sale	345,139
Loans transferred as secured borrowings	85,590		85,901
Investment securities	566,793		884,254
Intangible assets - servicing rights	187,732
Residential real estate, net	548,022		99,115
Non-performing residential loans	197,716		68,883
Investment in unconsolidated entities	138,168		32,318
Goodwill	107,099
Derivative assets	9,513		9,227
Accrued interest receivable	20,952		24,120
Other assets	98,383		25,021
VIE assets, at fair value	97,359,666
Total Assets	104,074,575		4,324,373
Liabilities:
Accounts payable, accrued expenses and other liabilities	189,172		30,094
Related-party payable	26,788		1,803
Dividends payable	90,130		73,796	51,629
Derivative liabilities	32,252		27,770
Secured financing agreements, net	1,312,044		1,305,812
Convertible senior notes, net	995,072
Loan transfer secured borrowings	86,682		87,893
Loan participation liability	95,000
VIE liabilities, at fair value	96,934,006
Total Liabilities	99,761,146		1,527,168
Commitments and contingencies
Starwood Property Trust, Inc. Stockholders' Equity:
Preferred stock
Common stock	1,959		1,361
Additional paid-in capital	4,295,058		2,721,353
Treasury stock	(10,642)		(10,642)
Accumulated other comprehensive income	69,287	60,285	79,675
Accumulated deficit	(85,339)		(72,401)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,270,323		2,719,346
Non-controlling interests in consolidated subsidiaries	43,106		77,859
Total Equity	4,313,429		2,797,205	2,301,238	1,765,147
Total Liabilities and Equity	104,074,575		4,324,373
Real Estate Investment Lending
Assets:
Cash and cash equivalents	282,553		169,427
Restricted cash	38,052		3,298
Loans held-for-investment, net	3,782,479		2,914,434
Loans held-for-sale	66,018
Loans transferred as secured borrowings	85,590		85,901
Investment securities	481,082		884,254
Investment in unconsolidated entities	35,413		32,318
Derivative assets	6,582		9,227
Accrued interest receivable	20,679		24,120
Other assets	41,415		19,299
Total Assets	4,839,863		4,142,278
Liabilities:
Accounts payable, accrued expenses and other liabilities	55,953		28,987
Related-party payable	20,780		1,803
Dividends payable	90,130		73,796
Derivative liabilities	27,082		27,770
Secured financing agreements, net	1,107,211		1,305,812
Convertible senior notes, net	995,072
Loan transfer secured borrowings	86,682		87,893
Loan participation liability	95,000
Total Liabilities	2,477,910		1,526,061
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	1,959		1,361
Additional paid-in capital	2,320,035		2,538,860
Treasury stock	(10,642)		(10,642)
Accumulated other comprehensive income	64,955		79,675
Accumulated deficit	(47,800)		(70,396)
Total Starwood Property Trust, Inc. Stockholders' Equity	2,328,507		2,538,858
Non-controlling interests in consolidated subsidiaries	33,446		77,359
Total Equity	2,361,953		2,616,217
Total Liabilities and Equity	4,839,863		4,142,278
Single Family Residential
Assets:
Cash and cash equivalents	30,089		8,244
Restricted cash	1,836		131
Residential real estate, net	548,022		99,115
Non-performing residential loans	197,716		68,883
Other assets	18,882		5,722
Total Assets	796,545		182,095
Liabilities:
Accounts payable, accrued expenses and other liabilities	10,489		1,107
Total Liabilities	10,489		1,107
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	791,817		182,493
Accumulated deficit	(7,258)		(2,005)
Total Starwood Property Trust, Inc. Stockholders' Equity	784,559		180,488
Non-controlling interests in consolidated subsidiaries	1,497		500
Total Equity	786,056		180,988
Total Liabilities and Equity	796,545		182,095
LNR
Assets:
Cash and cash equivalents	223,915
Restricted cash	42,818
Loans held-for-investment, net	7,783
Loans held-for-sale	279,121
Investment securities	410,071
Intangible assets - servicing rights	276,295
Investment in unconsolidated entities	106,675
Goodwill	107,099
Derivative assets	2,931
Accrued interest receivable	273
Other assets	38,799
Total Assets	1,495,780
Liabilities:
Accounts payable, accrued expenses and other liabilities	122,512
Related-party payable	6,008
Derivative liabilities	5,170
Secured financing agreements, net	204,833
Total Liabilities	338,523
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	1,183,206
Accumulated other comprehensive income	4,332
Accumulated deficit	(30,281)
Total Starwood Property Trust, Inc. Stockholders' Equity	1,157,257
Total Equity	1,157,257
Total Liabilities and Equity	1,495,780
Subtotal
Assets:
Cash and cash equivalents	536,557
Restricted cash	82,706
Loans held-for-investment, net	3,790,262
Loans held-for-sale	345,139
Loans transferred as secured borrowings	85,590
Investment securities	891,153
Intangible assets - servicing rights	276,295
Residential real estate, net	548,022
Non-performing residential loans	197,716
Investment in unconsolidated entities	142,088
Goodwill	107,099
Derivative assets	9,513
Accrued interest receivable	20,952
Other assets	99,096
Total Assets	7,132,188
Liabilities:
Accounts payable, accrued expenses and other liabilities	188,954
Related-party payable	26,788
Dividends payable	90,130
Derivative liabilities	32,252
Secured financing agreements, net	1,312,044
Convertible senior notes, net	995,072
Loan transfer secured borrowings	86,682
Loan participation liability	95,000
Total Liabilities	2,826,922
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	1,959
Additional paid-in capital	4,295,058
Treasury stock	(10,642)
Accumulated other comprehensive income	69,287
Accumulated deficit	(85,339)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,270,323
Non-controlling interests in consolidated subsidiaries	34,943
Total Equity	4,305,266
Total Liabilities and Equity	7,132,188
LNR VIEs
Assets:
Cash and cash equivalents	277
Investment securities	(324,360)
Intangible assets - servicing rights	(88,563)
Investment in unconsolidated entities	(3,920)
Other assets	(713)
VIE assets, at fair value	97,359,666
Total Assets	96,942,387
Liabilities:
Accounts payable, accrued expenses and other liabilities	218
VIE liabilities, at fair value	96,934,006
Total Liabilities	96,934,224
Starwood Property Trust, Inc. Stockholders' Equity:
Non-controlling interests in consolidated subsidiaries	8,163
Total Equity	8,163
Total Liabilities and Equity	$ 96,942,387