Segment Data - Balance sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Assets:
Cash and cash equivalents	$ 404,820		$ 368,815	$ 446,478		$ 255,187
Restricted cash	41,131		23,069
Loans held-for-investment, net	5,693,452		5,973,079
Loans held-for-sale	237,106		203,865
Loans transferred as secured borrowings	93,268		86,573
Investment securities	898,803		724,947
Properties, net	1,232,855		919,225
Intangible assets	177,053		201,570
Investment in unconsolidated entities	200,541		199,201
Goodwill	140,437		140,437
Derivative assets	42,692		45,091
Accrued interest receivable	30,036		34,314
Other assets	118,050		102,479
VIE assets, at fair value	80,076,117		76,675,689
Total Assets	89,386,361		85,698,354
Liabilities:
Accounts payable, accrued expenses and other liabilities	140,612		156,805
Related-party payable	20,318		40,955
Dividends payable	115,013		114,947
Derivative liabilities	17,870		5,196
Secured financing agreements, net	4,476,221		3,980,699
Convertible senior notes, net	1,334,424		1,323,795
Secured borrowings on transferred loans	94,668		88,000
VIE liabilities, at fair value	79,087,142		75,817,014
Total Liabilities	85,286,268		81,527,411
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,427		2,410
Additional paid-in capital	4,220,887		4,192,844
Treasury stock	(92,104)		(72,381)
Accumulated other comprehensive income (loss)	32,627	$ 33,457	29,729	45,901	$ 39,362	55,896
Retained earnings (accumulated deficit)	(103,373)		(12,286)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,060,464		4,140,316
Non-controlling interests in consolidated subsidiaries	39,629		30,627
Total Equity	4,100,093		4,170,943	$ 4,219,125		$ 3,882,912
Total Liabilities and Equity	89,386,361		85,698,354
Operating Segments and Corporate
Assets:
Cash and cash equivalents	403,664		367,837
Restricted cash	41,131		23,069
Loans held-for-investment, net	5,693,452		5,973,079
Loans held-for-sale	237,106		203,865
Loans transferred as secured borrowings	93,268		86,573
Investment securities	1,835,372		1,550,166
Properties, net	1,232,855		919,225
Intangible assets	206,625		213,399
Investment in unconsolidated entities	208,435		206,426
Goodwill	140,437		140,437
Derivative assets	42,692		45,091
Accrued interest receivable	30,036		34,314
Other assets	120,422		104,536
Total Assets	10,285,495		9,868,017
Liabilities:
Accounts payable, accrued expenses and other liabilities	139,830		156,116
Related-party payable	20,318		40,955
Dividends payable	115,013		114,947
Derivative liabilities	17,870		5,196
Secured financing agreements, net	4,476,221		3,980,699
Convertible senior notes, net	1,334,424		1,323,795
Secured borrowings on transferred loans	94,668		88,000
Total Liabilities	6,198,344		5,709,708
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,427		2,410
Additional paid-in capital	4,220,887		4,192,844
Treasury stock	(92,104)		(72,381)
Accumulated other comprehensive income (loss)	32,627		29,729
Retained earnings (accumulated deficit)	(103,373)		(12,286)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,060,464		4,140,316
Non-controlling interests in consolidated subsidiaries	26,687		17,993
Total Equity	4,087,151		4,158,309
Total Liabilities and Equity	10,285,495		9,868,017
Operating segment | Lending Segment
Assets:
Cash and cash equivalents	127,803		83,836
Restricted cash	17,359		9,775
Loans held-for-investment, net	5,687,399		5,973,079
Loans transferred as secured borrowings	93,268		86,573
Investment securities	784,463		511,966
Investment in unconsolidated entities	30,873		30,827
Derivative assets	32,446		33,412
Accrued interest receivable	29,028		34,028
Other assets	12,234		7,938
Total Assets	6,814,873		6,771,434
Liabilities:
Accounts payable, accrued expenses and other liabilities	9,352		18,822
Derivative liabilities	13,706		5,190
Secured financing agreements, net	2,600,851		2,341,897
Secured borrowings on transferred loans	94,668		88,000
Total Liabilities	2,718,577		2,453,909
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	2,062,358		2,477,987
Accumulated other comprehensive income (loss)	39,472		37,242
Retained earnings (accumulated deficit)	1,983,102		1,790,705
Total Starwood Property Trust, Inc. Stockholders' Equity	4,084,932		4,305,934
Non-controlling interests in consolidated subsidiaries	11,364		11,591
Total Equity	4,096,296		4,317,525
Total Liabilities and Equity	6,814,873		6,771,434
Operating segment | Investment and Servicing Segment
Assets:
Cash and cash equivalents	69,803		62,649
Restricted cash	16,092		8,826
Loans held-for-investment, net	6,053
Loans held-for-sale	237,106		203,865
Investment securities	1,050,909		1,038,200
Properties, net	220,340		150,497
Intangible assets	154,975		152,278
Investment in unconsolidated entities	55,432		53,145
Goodwill	140,437		140,437
Derivative assets	2,736		2,087
Accrued interest receivable	1,008		286
Other assets	74,481		71,505
Total Assets	2,029,372		1,883,775
Liabilities:
Accounts payable, accrued expenses and other liabilities	58,583		90,399
Related-party payable	555		423
Derivative liabilities	4,163		6
Secured financing agreements, net	503,864		422,260
Total Liabilities	567,165		513,088
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	1,183,776		1,146,926
Accumulated other comprehensive income (loss)	(6,973)		(3,714)
Retained earnings (accumulated deficit)	270,081		221,073
Total Starwood Property Trust, Inc. Stockholders' Equity	1,446,884		1,364,285
Non-controlling interests in consolidated subsidiaries	15,323		6,402
Total Equity	1,462,207		1,370,687
Total Liabilities and Equity	2,029,372		1,883,775
Operating segment | Property Segment
Assets:
Cash and cash equivalents	18,723		2,944
Restricted cash	7,680		4,468
Properties, net	1,012,515		768,728
Intangible assets	51,650		61,121
Investment in unconsolidated entities	122,130		122,454
Derivative assets	7,510		9,592
Other assets	32,544		23,657
Total Assets	1,252,752		992,964
Liabilities:
Accounts payable, accrued expenses and other liabilities	48,600		25,427
Derivative liabilities	1
Secured financing agreements, net	725,856		568,738
Total Liabilities	774,457		594,165
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	467,993		394,465
Accumulated other comprehensive income (loss)	128		(3,799)
Retained earnings (accumulated deficit)	10,174		8,133
Total Starwood Property Trust, Inc. Stockholders' Equity	478,295		398,799
Total Equity	478,295		398,799
Total Liabilities and Equity	1,252,752		992,964
Corporate
Assets:
Cash and cash equivalents	187,335		218,408
Other assets	1,163		1,436
Total Assets	188,498		219,844
Liabilities:
Accounts payable, accrued expenses and other liabilities	23,295		21,468
Related-party payable	19,763		40,532
Dividends payable	115,013		114,947
Secured financing agreements, net	645,650		647,804
Convertible senior notes, net	1,334,424		1,323,795
Total Liabilities	2,138,145		2,148,546
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,427		2,410
Additional paid-in capital	506,760		173,466
Treasury stock	(92,104)		(72,381)
Retained earnings (accumulated deficit)	(2,366,730)		(2,032,197)
Total Starwood Property Trust, Inc. Stockholders' Equity	(1,949,647)		(1,928,702)
Total Equity	(1,949,647)		(1,928,702)
Total Liabilities and Equity	188,498		219,844
Investment and Servicing VIEs
Assets:
Cash and cash equivalents	1,156		978
Investment securities	(936,569)		(825,219)
Intangible assets	(29,572)		(11,829)
Investment in unconsolidated entities	(7,894)		(7,225)
Other assets	(2,372)		(2,057)
VIE assets, at fair value	80,076,117		76,675,689
Total Assets	79,100,866		75,830,337
Liabilities:
Accounts payable, accrued expenses and other liabilities	782		689
VIE liabilities, at fair value	79,087,142		75,817,014
Total Liabilities	79,087,924		75,817,703
Starwood Property Trust, Inc. Stockholders' Equity:
Non-controlling interests in consolidated subsidiaries	12,942		12,634
Total Equity	12,942		12,634
Total Liabilities and Equity	$ 79,100,866		$ 75,830,337