Segment Data - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Interest income from loans	$ 138,599	$ 121,225	$ 371,094	$ 361,314
Interest income from investment securities	12,451	19,175	40,045	53,879
Servicing fees	14,842	22,918	47,572	70,921
Rental income	60,153	39,742	176,161	110,262
Other revenues	722	1,645	2,184	3,814
Total revenues	226,767	204,705	637,056	600,190
Costs and expenses:
Management fees	30,980	27,780	79,997	76,510
Interest expense	76,431	59,082	213,608	173,237
General and administrative	32,892	51,470	95,841	119,677
Acquisition and investment pursuit costs	1,024	1,509	2,232	5,682
Costs of rental operations	23,799	18,011	67,701	46,518
Depreciation and amortization	22,871	15,352	67,131	53,185
Loan loss allowance, net	(171)	2,127	(3,170)	3,395
Other expense	376	711	1,276	811
Total costs and expenses	188,202	176,042	524,616	479,015
Income before other income (loss), income taxes and non-controlling interests	38,565	28,663	112,440	121,175
Other income (loss):
Change in net assets related to consolidated VIEs	56,177	47,848	203,108	94,388
Change in fair value of servicing rights	(4,867)	(14,283)	(21,301)	(33,213)
Change in fair value of investment securities, net	(397)	(2,786)	(4,061)	(714)
Change in fair value of mortgage loans held-for-sale, net	19,485	49,996	45,484	70,122
(Loss) earnings from unconsolidated entities	(4,689)	4,305	27,763	12,849
Gain on sale of investments and other assets, net	11,877	10	17,004	165
Loss on derivative financial instruments, net	(24,224)	(2,328)	(66,159)	(6,793)
Foreign currency (loss), gain net	10,660	(3,214)	28,434	(20,580)
OTTI/Impairment			(109)
Loss on extinguishment of debt			(5,916)
Other income, net	28	269	484	10,998
Total other income (loss)	64,050	79,817	224,731	127,222
Income before income taxes	102,615	108,480	337,171	248,397
Income tax provision	(9,816)	(2,667)	(18,285)	(3,467)
Net income	92,799	105,813	318,886	244,930
Net income attributable to non-controlling interests	(4,371)	(47)	(10,720)	(1,034)
Net income attributable to Starwood Property Trust, Inc.	88,428	105,766	308,166	243,896
Operating Segments and Corporate
Revenues:
Interest income from loans	138,599	121,225	371,094	361,314
Interest income from investment securities	43,280	48,575	140,638	149,310
Servicing fees	23,235	37,873	87,405	111,705
Rental income	60,153	39,742	176,161	110,262
Other revenues	786	1,802	2,433	4,325
Total revenues	266,053	249,217	777,731	736,916
Costs and expenses:
Management fees	30,870	27,732	79,787	76,364
Interest expense	76,708	59,272	214,429	173,427
General and administrative	32,810	51,296	95,598	119,145
Acquisition and investment pursuit costs	1,024	1,509	2,232	5,682
Costs of rental operations	23,799	18,011	67,701	46,518
Depreciation and amortization	22,871	15,352	67,131	53,185
Loan loss allowance, net	(171)	2,127	(3,170)	3,395
Other expense	376	711	1,276	811
Total costs and expenses	188,287	176,010	524,984	478,527
Income before other income (loss), income taxes and non-controlling interests	77,766	73,207	252,747	258,389
Other income (loss):
Change in fair value of servicing rights	(5,652)	(14,006)	(28,956)	(33,710)
Change in fair value of investment securities, net	14,238	827	45,562	(43,486)
Change in fair value of mortgage loans held-for-sale, net	19,485	49,996	45,484	70,122
(Loss) earnings from unconsolidated entities	(2,658)	3,924	40,900	13,137
Gain on sale of investments and other assets, net	11,877	10	17,004	165
Loss on derivative financial instruments, net	(24,224)	(2,328)	(66,159)	(6,793)
Foreign currency (loss), gain net	10,660	(3,214)	28,434	(20,580)
OTTI/Impairment			(109)
Loss on extinguishment of debt			(5,916)
Other income, net	28	269	1,097	10,998
Total other income (loss)	23,754	35,478	77,341	(10,147)
Income before income taxes	101,520	108,685	330,088	248,242
Income tax provision	(9,816)	(2,667)	(18,285)	(3,467)
Net income	91,704	106,018	311,803	244,775
Net income attributable to non-controlling interests	(3,276)	(252)	(3,637)	(879)
Net income attributable to Starwood Property Trust, Inc.	88,428	105,766	308,166	243,896
Operating segment | Lending Segment
Revenues:
Interest income from loans	134,149	114,506	360,188	348,460
Interest income from investment securities	11,540	13,301	35,870	33,975
Servicing fees	142	195	568	560
Other revenues	181	99	553	180
Total revenues	146,012	128,101	397,179	383,175
Costs and expenses:
Management fees	482	525	1,405	1,295
Interest expense	27,929	22,678	72,372	67,585
General and administrative	5,302	5,067	14,872	13,529
Acquisition and investment pursuit costs	807	322	1,707	1,602
Depreciation and amortization	17		50
Loan loss allowance, net	(171)	2,127	(3,170)	3,395
Other expense	72		72
Total costs and expenses	34,438	30,719	87,308	87,406
Income before other income (loss), income taxes and non-controlling interests	111,574	97,382	309,871	295,769
Other income (loss):
Change in fair value of investment securities, net	276	207	299	(37)
Change in fair value of mortgage loans held-for-sale, net	(397)		(549)
(Loss) earnings from unconsolidated entities	848	852	2,548	2,544
Gain on sale of investments and other assets, net		10	(59)	165
Loss on derivative financial instruments, net	(10,813)	4,982	(30,274)	17,824
Foreign currency (loss), gain net	10,657	(3,839)	28,402	(23,501)
OTTI/Impairment			(109)
Total other income (loss)	571	2,212	258	(3,005)
Income before income taxes	112,145	99,594	310,129	292,764
Income tax provision	11		(331)	(75)
Net income	112,156	99,594	309,798	292,689
Net income attributable to non-controlling interests	(357)	(352)	(1,064)	(1,050)
Net income attributable to Starwood Property Trust, Inc.	111,799	99,242	308,734	291,639
Operating segment | Investment and Servicing Segment
Revenues:
Interest income from loans	4,450	6,719		12,854
Interest income from investment securities	31,740	35,274		115,335
Servicing fees	23,093	37,678		111,145
Rental income	12,490	10,516	138,795	25,214
Other revenues	441	1,692	430	4,110
Total revenues	72,214	91,879	139,225	268,658
Costs and expenses:
Management fees	18	24		54
Interest expense	5,710	4,877	32,466	11,443
General and administrative	24,167	43,711	3,471	95,726
Acquisition and investment pursuit costs	(28)	416	516	1,551
Costs of rental operations	5,139	4,872	51,843	11,595
Depreciation and amortization	5,002	4,482	52,288	11,263
Other expense	207	198	63	298
Total costs and expenses	40,215	58,580	140,647	131,930
Income before other income (loss), income taxes and non-controlling interests	31,999	33,299	(1,422)	136,728
Other income (loss):
Change in fair value of servicing rights	(5,652)	(14,006)		(33,710)
Change in fair value of investment securities, net	13,962	620		(43,449)
Change in fair value of mortgage loans held-for-sale, net	19,882	49,996		70,122
(Loss) earnings from unconsolidated entities	30,225	617	(28,782)	3,280
Gain on sale of investments and other assets, net	11,877		77
Loss on derivative financial instruments, net	(2,135)	(2,590)	(32,268)	(17,780)
Foreign currency (loss), gain net	4	632	16	2,962
Other income, net	28	35		112
Total other income (loss)	68,191	35,304	(60,957)	(18,463)
Income before income taxes	100,190	68,603	(62,379)	118,265
Income tax provision	(9,827)	(2,667)		(3,392)
Net income	90,363	65,936	(62,379)	114,873
Net income attributable to non-controlling interests	(2,919)	100		171
Net income attributable to Starwood Property Trust, Inc.	87,444	66,036	(62,379)	115,044
Operating segment | Property Segment
Revenues:
Interest income from loans			10,906
Interest income from investment securities			104,768
Servicing fees			86,837
Rental income	47,663	29,226	37,366	85,048
Other revenues	164	11	1,450	35
Total revenues	47,827	29,237	241,327	85,083
Costs and expenses:
Management fees			54
Interest expense	11,360	5,536	14,924	16,163
General and administrative	1,090	867	69,536	2,259
Acquisition and investment pursuit costs	245	759	9	1,517
Costs of rental operations	18,660	13,139	15,858	34,923
Depreciation and amortization	17,852	10,870	14,793	41,922
Other expense	97	513	1,141	513
Total costs and expenses	49,304	31,684	116,315	97,297
Income before other income (loss), income taxes and non-controlling interests	(1,477)	(2,447)	125,012	(12,214)
Other income (loss):
Change in fair value of servicing rights			(28,956)
Change in fair value of investment securities, net			45,263
Change in fair value of mortgage loans held-for-sale, net			46,033
(Loss) earnings from unconsolidated entities	(33,731)	2,455	67,134	7,313
Gain on sale of investments and other assets, net			16,986
Loss on derivative financial instruments, net	(11,276)	(4,720)	(3,617)	(6,837)
Foreign currency (loss), gain net	(1)	(7)	16	(41)
Other income, net			1,097	9,102
Total other income (loss)	(45,008)	(2,272)	143,956	9,537
Income before income taxes	(46,485)	(4,719)	268,968	(2,677)
Income tax provision			(17,954)
Net income	(46,485)	(4,719)	251,014	(2,677)
Net income attributable to non-controlling interests			(2,573)
Net income attributable to Starwood Property Trust, Inc.	(46,485)	(4,719)	248,441	(2,677)
Corporate
Costs and expenses:
Management fees	30,370	27,183	78,328	75,015
Interest expense	31,709	26,181	94,667	78,236
General and administrative	2,251	1,651	7,719	7,631
Acquisition and investment pursuit costs		12		1,012
Total costs and expenses	64,330	55,027	180,714	161,894
Income before other income (loss), income taxes and non-controlling interests	(64,330)	(55,027)	(180,714)	(161,894)
Other income (loss):
Loss on extinguishment of debt			(5,916)
Other income, net		234		1,784
Total other income (loss)		234	(5,916)	1,784
Income before income taxes	(64,330)	(54,793)	(186,630)	(160,110)
Net income	(64,330)	(54,793)	(186,630)	(160,110)
Net income attributable to Starwood Property Trust, Inc.	(64,330)	(54,793)	(186,630)	(160,110)
Investment and Servicing VIEs
Revenues:
Interest income from investment securities	(30,829)	(29,400)	(100,593)	(95,431)
Servicing fees	(8,393)	(14,955)	(39,833)	(40,784)
Other revenues	(64)	(157)	(249)	(511)
Total revenues	(39,286)	(44,512)	(140,675)	(136,726)
Costs and expenses:
Management fees	110	48	210	146
Interest expense	(277)	(190)	(821)	(190)
General and administrative	82	174	243	532
Total costs and expenses	(85)	32	(368)	488
Income before other income (loss), income taxes and non-controlling interests	(39,201)	(44,544)	(140,307)	(137,214)
Other income (loss):
Change in net assets related to consolidated VIEs	56,177	47,848	203,108	94,388
Change in fair value of servicing rights	785	(277)	7,655	497
Change in fair value of investment securities, net	(14,635)	(3,613)	(49,623)	42,772
(Loss) earnings from unconsolidated entities	(2,031)	381	(13,137)	(288)
Other income, net			(613)
Total other income (loss)	40,296	44,339	147,390	137,369
Income before income taxes	1,095	(205)	7,083	155
Net income	1,095	(205)	7,083	155
Net income attributable to non-controlling interests	$ (1,095)	$ 205	$ (7,083)	$ (155)