Segment Data - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Interest income from loans	$ 120,612	$ 122,557	$ 232,495	$ 240,089
Interest income from investment securities	12,370	15,301	27,594	34,704
Servicing fees	18,628	23,312	32,730	48,003
Rental income	58,966	37,843	116,008	70,520
Other revenues	993	979	1,462	2,169
Total revenues	211,569	199,992	410,289	395,485
Costs and expenses:
Management fees	24,633	23,767	49,017	48,730
Interest expense	71,317	57,635	137,177	114,155
General and administrative	32,520	35,409	62,949	68,207
Acquisition and investment pursuit costs	537	2,888	1,208	4,173
Costs of rental operations	23,024	15,852	43,902	28,507
Depreciation and amortization	22,032	19,073	44,260	37,833
Loan loss allowance, net	(2,694)	2,029	(2,999)	1,268
Other expense	142		900	100
Total costs and expenses	171,511	156,653	336,414	302,973
Income before other income (loss), income taxes and non-controlling interests	40,058	43,339	73,875	92,512
Other income (loss):
Change in net assets related to consolidated VIEs	77,761	50,707	146,931	46,540
Change in fair value of servicing rights	(8,001)	(12,191)	(16,434)	(18,930)
Change in fair value of investment securities, net	(2,493)	1,319	(3,664)	2,072
Change in fair value of mortgage loans held-for-sale, net	15,406	13,235	25,999	20,126
Earnings from unconsolidated entities	29,465	4,479	32,452	8,544
Gain (loss) on sale of investments and other assets, net	5,183	(90)	5,127	155
(Loss) gain on derivative financial instruments, net	(37,586)	20,253	(41,935)	(4,465)
Foreign currency (loss), gain net	12,910	(16,988)	17,774	(17,366)
OTTI/Impairment	(109)		(109)
Loss on extinguishment of debt			(5,916)
Other income, net	91	8,714	456	10,729
Total other income (loss)	92,627	69,438	160,681	47,405
Income before income taxes	132,685	112,777	234,556	139,917
Income tax benefit (provision)	(9,452)	(706)	(8,469)	(800)
Net income	123,233	112,071	226,087	139,117
Net income attributable to non-controlling interests	(5,853)	(598)	(6,349)	(987)
Net income attributable to Starwood Property Trust, Inc.	117,380	111,473	219,738	138,130
Operating Segments and Corporate
Revenues:
Interest income from loans	120,612	122,557	232,495	240,089
Interest income from investment securities	49,803	43,481	97,358	100,735
Servicing fees	33,879	37,455	64,170	73,832
Rental income	58,966	37,843	116,008	70,520
Other revenues	1,059	1,152	1,647	2,523
Total revenues	264,319	242,488	511,678	487,699
Costs and expenses:
Management fees	24,583	23,711	48,917	48,632
Interest expense	71,592	57,635	137,721	114,155
General and administrative	32,446	35,228	62,788	67,849
Acquisition and investment pursuit costs	537	2,888	1,208	4,173
Costs of rental operations	23,024	15,852	43,902	28,507
Depreciation and amortization	22,032	19,073	44,260	37,833
Loan loss allowance, net	(2,694)	2,029	(2,999)	1,268
Other expense	142		900	100
Total costs and expenses	171,662	156,416	336,697	302,517
Income before other income (loss), income taxes and non-controlling interests	92,657	86,072	174,981	185,182
Other income (loss):
Change in fair value of servicing rights	(13,667)	(11,034)	(23,304)	(19,704)
Change in fair value of investment securities, net	12,107	7,429	31,324	(44,313)
Change in fair value of mortgage loans held-for-sale, net	15,406	13,235	25,999	20,126
Earnings from unconsolidated entities	39,610	4,939	43,558	9,213
Gain (loss) on sale of investments and other assets, net	5,183	(90)	5,127	155
(Loss) gain on derivative financial instruments, net	(37,586)	20,253	(41,935)	(4,465)
Foreign currency (loss), gain net	12,910	(16,988)	17,774	(17,366)
OTTI/Impairment	(109)		(109)
Loss on extinguishment of debt			(5,916)
Other income, net	704	8,714	1,069	10,729
Total other income (loss)	34,558	26,458	53,587	(45,625)
Income before income taxes	127,215	112,530	228,568	139,557
Income tax benefit (provision)	(9,452)	(706)	(8,469)	(800)
Net income	117,763	111,824	220,099	138,757
Net income attributable to non-controlling interests	(383)	(351)	(361)	(627)
Net income attributable to Starwood Property Trust, Inc.	117,380	111,473	219,738	138,130
Operating segment | Lending Segment
Revenues:
Interest income from loans	116,993	119,296	226,039	233,954
Interest income from investment securities	11,611	11,046	24,330	20,674
Servicing fees	216	206	426	365
Other revenues	293	58	372	81
Total revenues	129,113	130,606	251,167	255,074
Costs and expenses:
Management fees	469	395	923	770
Interest expense	24,486	22,572	44,443	44,907
General and administrative	5,359	4,540	9,570	8,462
Acquisition and investment pursuit costs	385	942	900	1,280
Depreciation and amortization	16		33
Loan loss allowance, net	(2,694)	2,029	(2,999)	1,268
Total costs and expenses	28,021	30,478	52,870	56,687
Income before other income (loss), income taxes and non-controlling interests	101,092	100,128	198,297	198,387
Other income (loss):
Change in fair value of investment securities, net	(149)	(30)	23	(244)
Change in fair value of mortgage loans held-for-sale, net	(152)		(152)
Earnings from unconsolidated entities	1,230	1,224	1,700	1,692
Gain (loss) on sale of investments and other assets, net	(3)	(90)	(59)	155
(Loss) gain on derivative financial instruments, net	(14,926)	15,868	(19,461)	12,842
Foreign currency (loss), gain net	12,882	(17,840)	17,745	(19,662)
OTTI/Impairment	(109)		(109)
Total other income (loss)	(1,227)	(868)	(313)	(5,217)
Income before income taxes	99,865	99,260	197,984	193,170
Income tax benefit (provision)	(127)		(342)	(75)
Net income	99,738	99,260	197,642	193,095
Net income attributable to non-controlling interests	(353)	(348)	(707)	(698)
Net income attributable to Starwood Property Trust, Inc.	99,385	98,912	196,935	192,397
Operating segment | Investment and Servicing Segment
Revenues:
Interest income from loans	3,619	3,261	6,456	6,135
Interest income from investment securities	38,192	32,435	73,028	80,061
Servicing fees	33,663	37,249	63,744	73,467
Rental income	12,687	8,223	24,876	14,698
Other revenues	545	1,076	1,009	2,418
Total revenues	88,706	82,244	169,113	176,779
Costs and expenses:
Management fees	18	12	36	30
Interest expense	4,856	3,328	9,214	6,566
General and administrative	22,789	26,721	45,369	52,015
Acquisition and investment pursuit costs	53	780	37	1,135
Costs of rental operations	5,232	3,661	10,719	6,723
Depreciation and amortization	4,737	3,730	9,791	6,781
Other expense	176		934	100
Total costs and expenses	37,861	38,232	76,100	73,350
Income before other income (loss), income taxes and non-controlling interests	50,845	44,012	93,013	103,429
Other income (loss):
Change in fair value of servicing rights	(13,667)	(11,034)	(23,304)	(19,704)
Change in fair value of investment securities, net	12,256	7,459	31,301	(44,069)
Change in fair value of mortgage loans held-for-sale, net	15,558	13,235	26,151	20,126
Earnings from unconsolidated entities	35,892	1,286	36,909	2,663
Gain (loss) on sale of investments and other assets, net	5,109		5,109
(Loss) gain on derivative financial instruments, net	(2,179)	(3,945)	(1,482)	(15,190)
Foreign currency (loss), gain net	11	870	12	2,330
Other income, net	704	34	1,069	77
Total other income (loss)	53,684	7,905	75,765	(53,767)
Income before income taxes	104,529	51,917	168,778	49,662
Income tax benefit (provision)	(9,325)	(706)	(8,127)	(725)
Net income	95,204	51,211	160,651	48,937
Net income attributable to non-controlling interests	(30)	(3)	346	71
Net income attributable to Starwood Property Trust, Inc.	95,174	51,208	160,997	49,008
Operating segment | Property Segment
Revenues:
Rental income	46,279	29,620	91,132	55,822
Other revenues	221	18	266	24
Total revenues	46,500	29,638	91,398	55,846
Costs and expenses:
Interest expense	10,899	5,678	21,106	10,627
General and administrative	1,000	837	2,381	1,392
Acquisition and investment pursuit costs	99	166	271	758
Costs of rental operations	17,792	12,191	33,183	21,784
Depreciation and amortization	17,279	15,343	34,436	31,052
Other expense	(34)		(34)
Total costs and expenses	47,035	34,215	91,343	65,613
Income before other income (loss), income taxes and non-controlling interests	(535)	(4,577)	55	(9,767)
Other income (loss):
Earnings from unconsolidated entities	2,488	2,429	4,949	4,858
Gain (loss) on sale of investments and other assets, net	77		77
(Loss) gain on derivative financial instruments, net	(20,481)	8,330	(20,992)	(2,117)
Foreign currency (loss), gain net	17	(18)	17	(34)
Other income, net		8,680		9,102
Total other income (loss)	(17,899)	19,421	(15,949)	11,809
Income before income taxes	(18,434)	14,844	(15,894)	2,042
Net income	(18,434)	14,844	(15,894)	2,042
Net income attributable to Starwood Property Trust, Inc.	(18,434)	14,844	(15,894)	2,042
Corporate
Costs and expenses:
Management fees	24,096	23,304	47,958	47,832
Interest expense	31,351	26,057	62,958	52,055
General and administrative	3,298	3,130	5,468	5,980
Acquisition and investment pursuit costs		1,000		1,000
Total costs and expenses	58,745	53,491	116,384	106,867
Income before other income (loss), income taxes and non-controlling interests	(58,745)	(53,491)	(116,384)	(106,867)
Other income (loss):
Loss on extinguishment of debt			(5,916)
Other income, net				1,550
Total other income (loss)			(5,916)	1,550
Income before income taxes	(58,745)	(53,491)	(122,300)	(105,317)
Net income	(58,745)	(53,491)	(122,300)	(105,317)
Net income attributable to Starwood Property Trust, Inc.	(58,745)	(53,491)	(122,300)	(105,317)
Investment and Servicing VIEs
Revenues:
Interest income from investment securities	(37,433)	(28,180)	(69,764)	(66,031)
Servicing fees	(15,251)	(14,143)	(31,440)	(25,829)
Other revenues	(66)	(173)	(185)	(354)
Total revenues	(52,750)	(42,496)	(101,389)	(92,214)
Costs and expenses:
Management fees	50	56	100	98
Interest expense	(275)		(544)
General and administrative	74	181	161	358
Total costs and expenses	(151)	237	(283)	456
Income before other income (loss), income taxes and non-controlling interests	(52,599)	(42,733)	(101,106)	(92,670)
Other income (loss):
Change in net assets related to consolidated VIEs	77,761	50,707	146,931	46,540
Change in fair value of servicing rights	5,666	(1,157)	6,870	774
Change in fair value of investment securities, net	(14,600)	(6,110)	(34,988)	46,385
Earnings from unconsolidated entities	(10,145)	(460)	(11,106)	(669)
Other income, net	(613)		(613)
Total other income (loss)	58,069	42,980	107,094	93,030
Income before income taxes	5,470	247	5,988	360
Net income	5,470	247	5,988	360
Net income attributable to non-controlling interests	$ (5,470)	$ (247)	$ (5,988)	$ (360)