Segment and Geographic Data - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Interest income from loans	$ 191,466	$ 151,704	$ 374,882	$ 289,324
Interest income from investment securities	22,545	10,790	40,177	26,059
Servicing fees	9,008	17,315	33,441	43,382
Rental income	87,297	88,891	171,130	170,001
Other revenues	865	856	2,031	1,377
Total revenues	311,181	269,556	621,661	530,143
Costs and expenses:
Management fees	22,523	27,494	45,989	58,136
Interest expense	130,126	91,592	264,798	178,775
General and administrative	37,578	35,528	72,508	67,670
Acquisition and investment pursuit costs	74	1,561	416	1,938
Costs of rental operations	30,655	32,897	60,306	62,590
Depreciation and amortization	28,552	37,150	57,806	68,894
Loan loss provision, net	2,518	25,259	3,281	26,797
Other expense	1,443	497	1,654	601
Total costs and expenses	253,469	251,978	506,758	465,401
Other income (loss):
Change in net assets related to consolidated VIEs	55,158	43,946	102,994	96,599
Change in fair value of servicing rights	(916)	(2,203)	(1,683)	(8,017)
Change in fair value of investment securities, net	667	7,702	729	7,553
Change in fair value of mortgage loans held-for-sale, net	21,891	14,833	33,157	22,633
Earnings (loss) from unconsolidated entities	8,817	5,470	(34,383)	4,008
(Loss) gain on derivative financial instruments, net	2,515	13,437	7,000	24,097
(Loss) gain on derivative financial instruments, net	(32)	32,622	(2,239)	15,763
Foreign currency gain (loss), net	(7,017)	(13,264)	(1,470)	285
Loss on extinguishment of debt	(2,816)	(186)	(6,114)	(186)
Other (loss) income, net		498	(73)	606
Total other income	78,267	102,855	97,918	163,341
Income before income taxes	135,979	120,433	212,821	228,083
Income tax provision	(3,533)	(3,343)	(3,867)	(6,199)
Net income	132,446	117,090	208,954	221,884
Net income attributable to Starwood Property Trust, Inc.	(5,430)	(7,860)	(11,555)	(12,722)
Net income attributable to Starwood Property Trust, Inc.	127,016	109,230	197,399	209,162
Operating Segments and Corporate
Revenues:
Interest income from loans	191,466	151,704	374,882	289,324
Interest income from investment securities	56,398	39,402	101,484	88,240
Servicing fees	15,970	24,737	43,336	58,336
Rental income	87,297	88,891	171,130	170,001
Other revenues	868	907	2,052	1,482
Total revenues	351,999	305,641	692,884	607,383
Costs and expenses:
Management fees	22,478	27,388	45,895	57,937
Interest expense	130,290	91,867	265,122	179,320
General and administrative	37,486	35,444	72,328	67,500
Acquisition and investment pursuit costs	74	1,561	416	1,938
Costs of rental operations	30,655	32,897	60,306	62,590
Depreciation and amortization	28,552	37,150	57,806	68,894
Loan loss provision, net	2,518	25,259	3,281	26,797
Other expense	1,443	497	1,654	601
Total costs and expenses	253,496	252,063	506,808	465,577
Other income (loss):
Change in fair value of servicing rights	(1,159)	(3,255)	(1,674)	(12,423)
Change in fair value of investment securities, net	14,867	15,592	31,313	28,867
Change in fair value of mortgage loans held-for-sale, net	21,891	14,833	33,157	22,633
Earnings (loss) from unconsolidated entities	9,290	6,190	(33,344)	5,715
(Loss) gain on derivative financial instruments, net	2,515	13,437	7,000	24,097
(Loss) gain on derivative financial instruments, net	(32)	32,622	(2,239)	15,763
Foreign currency gain (loss), net	(7,017)	(13,264)	(1,470)	285
Loss on extinguishment of debt	(2,816)	(186)	(6,114)	(186)
Other (loss) income, net		498	(73)	606
Total other income	37,539	66,467	26,556	85,357
Income before income taxes	136,042	120,045	212,632	227,163
Income tax provision	(3,533)	(3,343)	(3,867)	(6,199)
Net income	132,509	116,702	208,765	220,964
Net income attributable to Starwood Property Trust, Inc.	(5,493)	(7,472)	(11,366)	(11,802)
Net income attributable to Starwood Property Trust, Inc.	127,016	109,230	197,399	209,162
Operating segment | Commercial and Residential Lending Segment
Revenues:
Interest income from loans	163,071	148,268	317,666	283,240
Interest income from investment securities	24,367	8,930	44,275	23,369
Servicing fees	90	50	213	215
Other revenues	252	224	456	418
Total revenues	187,780	157,472	362,610	307,242
Costs and expenses:
Management fees	353	463	764	943
Interest expense	58,564	34,826	120,168	66,847
General and administrative	6,754	6,251	13,522	12,946
Acquisition and investment pursuit costs	160	1,692	409	1,912
Costs of rental operations	741		760
Depreciation and amortization	285	16	356	33
Loan loss provision, net	2,096	25,259	2,085	26,797
Other expense	76	77	153	154
Total costs and expenses	69,029	68,584	138,217	109,632
Other income (loss):
Change in fair value of investment securities, net	(948)	482	(2,642)	(222)
Change in fair value of mortgage loans held-for-sale, net	5,363	184	6,749	(1,508)
Earnings (loss) from unconsolidated entities	5,492	1,803	6,069	3,247
(Loss) gain on derivative financial instruments, net	239	135	2,994	414
(Loss) gain on derivative financial instruments, net	5,592	19,467	(3,705)	8,649
Foreign currency gain (loss), net	(6,927)	(13,264)	(1,688)	286
Other (loss) income, net				43
Total other income	8,811	8,807	7,777	10,909
Income before income taxes	127,562	97,695	232,170	208,519
Income tax provision	(1,832)	(1,720)	(1,584)	(2,667)
Net income	125,730	95,975	230,586	205,852
Net income attributable to Starwood Property Trust, Inc.	(21)	(361)	(392)	(722)
Net income attributable to Starwood Property Trust, Inc.	125,709	95,614	230,194	205,130
Operating segment | Infrastructure Lending Segment
Revenues:
Interest income from loans	25,291		52,206
Interest income from investment securities	868		1,753
Other revenues	7		693
Total revenues	26,166		54,652
Costs and expenses:
Interest expense	16,258		34,835
General and administrative	4,830		9,309
Acquisition and investment pursuit costs	14		30
Loan loss provision, net	422		1,196
Total costs and expenses	21,524		45,370
Other income (loss):
(Loss) gain on derivative financial instruments, net	2,276		3,066
(Loss) gain on derivative financial instruments, net	(2,833)		(3,228)
Foreign currency gain (loss), net	(83)		217
Loss on extinguishment of debt	(2,816)		(6,120)
Total other income	(3,456)		(6,065)
Income before income taxes	1,186		3,217
Income tax provision	186		271
Net income	1,372		3,488
Net income attributable to Starwood Property Trust, Inc.	1,372		3,488
Operating segment | Investing and Servicing Segment
Revenues:
Interest income from loans	3,104	3,436	5,010	6,084
Interest income from investment securities	31,163	30,472	55,456	64,871
Servicing fees	15,880	24,687	43,123	58,121
Rental income	14,971	14,490	28,283	28,890
Other revenues	515	516	711	744
Total revenues	65,633	73,601	132,583	158,710
Costs and expenses:
Management fees	18	18	36	36
Interest expense	8,515	5,807	16,261	10,902
General and administrative	20,177	23,855	39,028	44,875
Acquisition and investment pursuit costs	(100)	(79)	(23)	72
Costs of rental operations	6,789	6,906	13,484	13,111
Depreciation and amortization	5,191	5,396	10,478	10,654
Other expense	194	420	194	447
Total costs and expenses	40,784	42,323	79,458	80,097
Other income (loss):
Change in fair value of servicing rights	(1,159)	(3,255)	(1,674)	(12,423)
Change in fair value of investment securities, net	15,815	15,110	33,955	29,089
Change in fair value of mortgage loans held-for-sale, net	16,528	14,649	26,408	24,141
Earnings (loss) from unconsolidated entities	2,754	1,454	3,348	3,050
(Loss) gain on derivative financial instruments, net		10,361	940	16,800
(Loss) gain on derivative financial instruments, net	(6,953)	(398)	(10,385)	4,644
Foreign currency gain (loss), net	1	1		(2)
Loss on extinguishment of debt		(186)		(186)
Other (loss) income, net		9		57
Total other income	26,986	37,745	52,592	65,170
Income before income taxes	51,835	69,023	105,717	143,783
Income tax provision	(1,887)	(1,012)	(2,296)	(1,660)
Net income	49,948	68,011	103,421	142,123
Net income attributable to Starwood Property Trust, Inc.	(117)	(2,427)	98	(3,943)
Net income attributable to Starwood Property Trust, Inc.	49,831	65,584	103,519	138,180
Operating segment | Property Segment
Revenues:
Rental income	72,326	74,401	142,847	141,111
Other revenues	88	81	166	182
Total revenues	72,414	74,482	143,013	141,293
Costs and expenses:
Interest expense	19,132	19,380	38,122	35,914
General and administrative	1,706	1,971	3,224	3,830
Acquisition and investment pursuit costs		(52)		(46)
Costs of rental operations	23,125	25,991	46,062	49,479
Depreciation and amortization	23,076	31,738	46,972	58,207
Other expense	1,173		1,307
Total costs and expenses	68,212	79,028	135,687	147,384
Other income (loss):
Earnings (loss) from unconsolidated entities	1,044	2,933	(42,761)	(582)
(Loss) gain on derivative financial instruments, net		2,941		6,883
(Loss) gain on derivative financial instruments, net	(11,147)	19,920	(9,857)	21,839
Foreign currency gain (loss), net	(8)	(1)	1	1
Other (loss) income, net		489		506
Total other income	(10,111)	26,282	(52,617)	28,647
Income before income taxes	(5,909)	21,736	(45,291)	22,556
Income tax provision		(611)	(258)	(1,872)
Net income	(5,909)	21,125	(45,549)	20,684
Net income attributable to Starwood Property Trust, Inc.	(5,355)	(4,684)	(11,072)	(7,137)
Net income attributable to Starwood Property Trust, Inc.	(11,264)	16,441	(56,621)	13,547
Corporate
Revenues:
Other revenues	6	86	26	138
Total revenues	6	86	26	138
Costs and expenses:
Management fees	22,107	26,907	45,095	56,958
Interest expense	27,821	31,854	55,736	65,657
General and administrative	4,019	3,367	7,245	5,849
Total costs and expenses	53,947	62,128	108,076	128,464
Other income (loss):
(Loss) gain on derivative financial instruments, net	15,309	(6,367)	24,936	(19,369)
Loss on extinguishment of debt			6
Other (loss) income, net			(73)
Total other income	15,309	(6,367)	24,869	(19,369)
Income before income taxes	(38,632)	(68,409)	(83,181)	(147,695)
Net income	(38,632)	(68,409)	(83,181)	(147,695)
Net income attributable to Starwood Property Trust, Inc.	(38,632)	(68,409)	(83,181)	(147,695)
LNR VIEs
Revenues:
Interest income from investment securities	(33,853)	(28,612)	(61,307)	(62,181)
Servicing fees	(6,962)	(7,422)	(9,895)	(14,954)
Other revenues	(3)	(51)	(21)	(105)
Total revenues	(40,818)	(36,085)	(71,223)	(77,240)
Costs and expenses:
Management fees	45	106	94	199
Interest expense	(164)	(275)	(324)	(545)
General and administrative	92	84	180	170
Total costs and expenses	(27)	(85)	(50)	(176)
Other income (loss):
Change in net assets related to consolidated VIEs	55,158	43,946	102,994	96,599
Change in fair value of servicing rights	243	1,052	(9)	4,406
Change in fair value of investment securities, net	(14,200)	(7,890)	(30,584)	(21,314)
Earnings (loss) from unconsolidated entities	(473)	(720)	(1,039)	(1,707)
Total other income	40,728	36,388	71,362	77,984
Income before income taxes	(63)	388	189	920
Net income	(63)	388	189	920
Net income attributable to Starwood Property Trust, Inc.	$ 63	$ (388)	$ (189)	$ (920)