Segment Data - Results of Operations (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Interest income from loans		$ 122,557	$ 118,292	$ 240,089	$ 236,721
Interest income from investment securities		15,301	23,810	34,704	51,554
Servicing fees		23,312	30,154	48,003	58,411
Rental income		37,843	5,014	70,520	7,686
Other revenues		979	1,390	2,169	3,137
Total revenues		199,992	178,660	395,485	357,509
Costs and expenses:
Management fees		23,767	26,821	48,730	54,789
Interest expense		57,635	49,799	114,155	100,333
General and administrative		35,409	41,404	68,207	76,668
Acquisition and investment pursuit costs		2,888	4,867	4,173	6,053
Costs of rental operations		15,852	1,211	28,507	2,909
Depreciation and amortization		19,073	5,828	37,833	9,913
Loan loss allowance, net		2,029	2,661	1,268	2,978
Other expense				100	375
Total costs and expenses		156,653	132,591	302,973	254,018
Income before other income (loss), income taxes and non-controlling interests		43,339	46,069	92,512	103,491
Other income (loss):
Change in net assets related to consolidated VIEs		50,707	55,873	46,540	103,734
Change in fair value of servicing rights		(12,191)	(2,652)	(18,930)	(4,194)
Change in fair value of investment securities, net		1,319	1,446	2,072	947
Change in fair value of mortgage loans held-for-sale, net		13,235	10,831	20,126	31,962
Earnings from unconsolidated entities		4,479	8,951	8,544	15,041
(Loss) gain on sale of investments and other assets, net		(90)	209	155	17,407
Gain (loss) on derivative financial instruments, net		20,253	(19,530)	(4,465)	5,093
Foreign currency (loss), gain net		(16,988)	20,854	(17,366)	(9,453)
Loss on extinguishment of debt			(629)		(5,921)
Other income, net		8,714	10	10,729	55
Total other income (loss)		69,438	75,363	47,405	154,671
Income before income taxes		112,777	121,432	139,917	258,162
Income tax benefit (provision)		(706)	(3,792)	(800)	(19,743)
Net income		112,071	117,640	139,117	238,419
Net income attributable to non-controlling interests		(598)	(492)	(987)	(908)
Net income attributable to Starwood Property Trust, Inc.		111,473	117,148	138,130	237,511
Investment and Servicing Segment
Other income (loss):
(Loss) gain on sale of investments and other assets, net	$ 17,100
Operating Segments and Corporate
Revenues:
Interest income from loans		122,557	118,292	240,089	236,721
Interest income from investment securities		43,481	64,322	100,735	111,314
Servicing fees		37,455	54,447	73,832	105,479
Rental income		37,843	5,014	70,520	7,686
Other revenues		1,152	1,635	2,523	3,644
Total revenues		242,488	243,710	487,699	464,844
Costs and expenses:
Management fees		23,711	26,770	48,632	54,688
Interest expense		57,635	49,799	114,155	100,333
General and administrative		35,228	41,226	67,849	76,304
Acquisition and investment pursuit costs		2,888	4,867	4,173	6,053
Costs of rental operations		15,852	1,211	28,507	2,909
Depreciation and amortization		19,073	5,828	37,833	9,913
Loan loss allowance, net		2,029	2,661	1,268	2,978
Other expense				100	375
Total costs and expenses		156,416	132,362	302,517	253,553
Income before other income (loss), income taxes and non-controlling interests		86,072	111,348	185,182	211,291
Other income (loss):
Change in fair value of servicing rights		(11,034)	(8,381)	(19,704)	(13,256)
Change in fair value of investment securities, net		7,429	(2,681)	(44,313)	5,293
Change in fair value of mortgage loans held-for-sale, net		13,235	10,831	20,126	31,962
Earnings from unconsolidated entities		4,939	9,243	9,213	15,463
(Loss) gain on sale of investments and other assets, net		(90)	209	155	17,407
Gain (loss) on derivative financial instruments, net		20,253	(19,530)	(4,465)	5,093
Foreign currency (loss), gain net		(16,988)	20,854	(17,366)	(9,453)
Loss on extinguishment of debt			(629)		(5,921)
Other income, net		8,714	10	10,729	55
Total other income (loss)		26,458	9,926	(45,625)	46,643
Income before income taxes		112,530	121,274	139,557	257,934
Income tax benefit (provision)		(706)	(3,792)	(800)	(19,743)
Net income		111,824	117,482	138,757	238,191
Net income attributable to non-controlling interests		(351)	(334)	(627)	(680)
Net income attributable to Starwood Property Trust, Inc.		111,473	117,148	138,130	237,511
Operating segment | Lending Segment
Revenues:
Interest income from loans		119,296	113,928	233,954	227,400
Interest income from investment securities		11,046	17,050	20,674	39,346
Servicing fees		206	98	365	182
Other revenues		58	334	81	413
Total revenues		130,606	131,410	255,074	267,341
Costs and expenses:
Management fees		395	367	770	755
Interest expense		22,572	20,197	44,907	41,720
General and administrative		4,540	6,083	8,462	10,941
Acquisition and investment pursuit costs		942	224	1,280	997
Loan loss allowance, net		2,029	2,661	1,268	2,978
Total costs and expenses		30,478	29,532	56,687	57,391
Income before other income (loss), income taxes and non-controlling interests		100,128	101,878	198,387	209,950
Other income (loss):
Change in fair value of investment securities, net		(30)	510	(244)	171
Earnings from unconsolidated entities		1,224	1,361	1,692	2,216
(Loss) gain on sale of investments and other assets, net		(90)	209	155	307
Gain (loss) on derivative financial instruments, net		15,868	(23,954)	12,842	8,909
Foreign currency (loss), gain net		(17,840)	21,181	(19,662)	(8,155)
Total other income (loss)		(868)	(693)	(5,217)	3,448
Income before income taxes		99,260	101,185	193,170	213,398
Income tax benefit (provision)				(75)	30
Net income		99,260	101,185	193,095	213,428
Net income attributable to non-controlling interests		(348)	(334)	(698)	(680)
Net income attributable to Starwood Property Trust, Inc.		98,912	100,851	192,397	212,748
Operating segment | Investment and Servicing Segment
Revenues:
Interest income from loans		3,261	4,364	6,135	9,321
Interest income from investment securities		32,435	47,272	80,061	71,968
Servicing fees		37,249	54,349	73,467	105,297
Rental income		8,223	1,478	14,698	4,150
Other revenues		1,076	1,301	2,418	3,231
Total revenues		82,244	108,764	176,779	193,967
Costs and expenses:
Management fees		12	18	30	36
Interest expense		3,328	2,751	6,566	4,870
General and administrative		26,721	32,626	52,015	61,815
Acquisition and investment pursuit costs		780	505	1,135	718
Costs of rental operations		3,661	878	6,723	2,576
Depreciation and amortization		3,730	4,213	6,781	8,298
Other expense				100	375
Total costs and expenses		38,232	40,991	73,350	78,688
Income before other income (loss), income taxes and non-controlling interests		44,012	67,773	103,429	115,279
Other income (loss):
Change in fair value of servicing rights		(11,034)	(8,381)	(19,704)	(13,256)
Change in fair value of investment securities, net		7,459	(3,191)	(44,069)	5,122
Change in fair value of mortgage loans held-for-sale, net		13,235	10,831	20,126	31,962
Earnings from unconsolidated entities		1,286	5,328	2,663	8,052
(Loss) gain on sale of investments and other assets, net					17,100
Gain (loss) on derivative financial instruments, net		(3,945)	4,274	(15,190)	(3,733)
Foreign currency (loss), gain net		870	(120)	2,330	(1,291)
Other income, net		34	10	77	41
Total other income (loss)		7,905	8,751	(53,767)	43,997
Income before income taxes		51,917	76,524	49,662	159,276
Income tax benefit (provision)		(706)	(3,792)	(725)	(19,773)
Net income		51,211	72,732	48,937	139,503
Net income attributable to non-controlling interests		(3)		71
Net income attributable to Starwood Property Trust, Inc.		51,208	72,732	49,008	139,503
Operating segment | Property Segment
Revenues:
Rental income		29,620	3,536	55,822	3,536
Other revenues		18		24
Total revenues		29,638	3,536	55,846	3,536
Costs and expenses:
Interest expense		5,678	877	10,627	877
General and administrative		837	174	1,392	176
Acquisition and investment pursuit costs		166	4,262	758	4,262
Costs of rental operations		12,191	333	21,784	333
Depreciation and amortization		15,343	1,615	31,052	1,615
Total costs and expenses		34,215	7,261	65,613	7,263
Income before other income (loss), income taxes and non-controlling interests		(4,577)	(3,725)	(9,767)	(3,727)
Other income (loss):
Earnings from unconsolidated entities		2,429	2,554	4,858	5,195
Gain (loss) on derivative financial instruments, net		8,330	150	(2,117)	(83)
Foreign currency (loss), gain net		(18)	(207)	(34)	(7)
Other income, net		8,680		9,102
Total other income (loss)		19,421	2,497	11,809	5,105
Income before income taxes		14,844	(1,228)	2,042	1,378
Net income		14,844	(1,228)	2,042	1,378
Net income attributable to Starwood Property Trust, Inc.		14,844	(1,228)	2,042	1,378
Corporate
Costs and expenses:
Management fees		23,304	26,385	47,832	53,897
Interest expense		26,057	25,974	52,055	52,866
General and administrative		3,130	2,343	5,980	3,372
Acquisition and investment pursuit costs		1,000	(124)	1,000	76
Total costs and expenses		53,491	54,578	106,867	110,211
Income before other income (loss), income taxes and non-controlling interests		(53,491)	(54,578)	(106,867)	(110,211)
Other income (loss):
Loss on extinguishment of debt			(629)		(5,921)
Other income, net				1,550	14
Total other income (loss)			(629)	1,550	(5,907)
Income before income taxes		(53,491)	(55,207)	(105,317)	(116,118)
Net income		(53,491)	(55,207)	(105,317)	(116,118)
Net income attributable to Starwood Property Trust, Inc.		(53,491)	(55,207)	(105,317)	(116,118)
Investment and Servicing VIEs
Revenues:
Interest income from investment securities		(28,180)	(40,512)	(66,031)	(59,760)
Servicing fees		(14,143)	(24,293)	(25,829)	(47,068)
Other revenues		(173)	(245)	(354)	(507)
Total revenues		(42,496)	(65,050)	(92,214)	(107,335)
Costs and expenses:
Management fees		56	51	98	101
General and administrative		181	178	358	364
Total costs and expenses		237	229	456	465
Income before other income (loss), income taxes and non-controlling interests		(42,733)	(65,279)	(92,670)	(107,800)
Other income (loss):
Change in net assets related to consolidated VIEs		50,707	55,873	46,540	103,734
Change in fair value of servicing rights		(1,157)	5,729	774	9,062
Change in fair value of investment securities, net		(6,110)	4,127	46,385	(4,346)
Earnings from unconsolidated entities		(460)	(292)	(669)	(422)
Total other income (loss)		42,980	65,437	93,030	108,028
Income before income taxes		247	158	360	228
Net income		247	158	360	228
Net income attributable to non-controlling interests		$ (247)	$ (158)	$ (360)	$ (228)