Segment Data - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Interest income from loans	$ 171,103	$ 191,466	$ 388,530	$ 374,882
Interest income from investment securities	14,644	22,545	29,884	40,177
Servicing fees	6,658	9,008	11,451	33,441
Rental income	72,710	87,297	146,856	171,130
Other revenues	491	865	1,445	2,031
Total revenues	265,606	311,181	578,166	621,661
Costs and expenses:
Management fees	23,115	22,523	63,843	45,989
Interest expense	101,493	130,126	221,518	264,798
General and administrative	32,677	37,578	71,379	72,508
Acquisition and investment pursuit costs	1,590	74	2,499	416
Costs of rental operations	29,632	30,655	57,846	60,306
Depreciation and amortization	23,421	28,552	47,401	57,806
Credit loss provision, net	10,202	2,518	58,871	3,281
Other expense	102	1,443	490	1,654
Total costs and expenses	222,232	253,469	523,847	506,758
Other income (loss):
Change in net assets related to consolidated VIEs	51,261	55,158	5,768	102,994
Change in fair value of servicing rights	(2,569)	(916)	(2,962)	(1,683)
Change in fair value of investment securities, net	827	667	3,331	729
Change in fair value of mortgage loans, net	34,450	21,891	18,316	33,157
Earnings (loss) from unconsolidated entities	28,776	8,817	28,873	(34,383)
(Loss) gain on sale of investments and other assets, net	6,472	2,515	6,768	7,000
(Loss) gain on derivative financial instruments, net	(16,098)	(32)	(6,388)	(2,239)
Foreign currency gain (loss), net	7,173	(7,017)	(27,313)	(1,470)
Loss on extinguishment of debt	(2,207)	(2,816)	(2,377)	(6,114)
Other income, net	204		330	(73)
Total other income	108,289	78,267	24,346	97,918
Income before income taxes	151,663	135,979	78,665	212,821
Income tax (provision) benefit	1,298	(3,533)	8,027	(3,867)
Net income	152,961	132,446	86,692	208,954
Net income attributable to Starwood Property Trust, Inc.	(13,305)	(5,430)	(13,805)	(11,555)
Net income attributable to Starwood Property Trust, Inc.	139,656	127,016	72,887	197,399
Operating Segments and Corporate
Revenues:
Interest income from loans	171,103	191,466	388,530	374,882
Interest income from investment securities	42,952	56,398	87,081	101,484
Servicing fees	8,733	15,970	15,347	43,336
Rental income	72,710	87,297	146,856	171,130
Other revenues	492	868	1,448	2,052
Total revenues	295,990	351,999	639,262	692,884
Costs and expenses:
Management fees	23,113	22,478	63,810	45,895
Interest expense	101,493	130,290	221,680	265,122
General and administrative	32,594	37,486	71,212	72,328
Acquisition and investment pursuit costs	1,590	74	2,499	416
Costs of rental operations	29,632	30,655	57,846	60,306
Depreciation and amortization	23,421	28,552	47,401	57,806
Credit loss provision, net	10,202	2,518	58,871	3,281
Other expense	102	1,443	490	1,654
Total costs and expenses	222,147	253,496	523,809	506,808
Other income (loss):
Change in fair value of servicing rights	5,328	(1,159)	5,646	(1,674)
Change in fair value of investment securities, net	13,395	14,867	(61,700)	31,313
Change in fair value of mortgage loans, net	34,450	21,891	18,316	33,157
Earnings (loss) from unconsolidated entities	29,079	9,290	29,750	(33,344)
(Loss) gain on sale of investments and other assets, net	6,472	2,515	6,768	7,000
(Loss) gain on derivative financial instruments, net	(16,098)	(32)	(6,388)	(2,239)
Foreign currency gain (loss), net	7,173	(7,017)	(27,313)	(1,470)
Loss on extinguishment of debt	(2,207)	(2,816)	(2,377)	(6,114)
Other income, net	204		330	(73)
Total other income	77,796	37,539	(36,968)	26,556
Income before income taxes	151,639	136,042	78,485	212,632
Income tax (provision) benefit	1,298	(3,533)	8,027	(3,867)
Net income	152,937	132,509	86,512	208,765
Net income attributable to Starwood Property Trust, Inc.	(13,281)	(5,493)	(13,625)	(11,366)
Net income attributable to Starwood Property Trust, Inc.	139,656	127,016	72,887	197,399
Operating segment | Commercial and Residential Lending Segment
Revenues:
Interest income from loans	150,136	163,071	342,517	317,666
Interest income from investment securities	17,345	24,367	35,973	44,275
Servicing fees	142	90	314	213
Rental income	690		768
Other revenues	54	252	232	456
Total revenues	168,367	187,780	379,804	362,610
Costs and expenses:
Management fees	339	353	690	764
Interest expense	41,871	58,564	95,821	120,168
General and administrative	8,615	6,754	16,747	13,522
Acquisition and investment pursuit costs	578	160	1,438	409
Costs of rental operations	988	741	1,766	760
Depreciation and amortization	430	285	845	356
Credit loss provision, net	11,294	2,096	51,511	2,085
Other expense	76	76	153	153
Total costs and expenses	64,191	69,029	168,971	138,217
Other income (loss):
Change in fair value of investment securities, net	5,454	(948)	(22,425)	(2,642)
Change in fair value of mortgage loans, net	33,010	5,363	(2,507)	6,749
Earnings (loss) from unconsolidated entities	671	5,492	722	6,069
(Loss) gain on sale of investments and other assets, net	(961)	239	(961)	2,994
(Loss) gain on derivative financial instruments, net	(11,736)	5,592	19,069	(3,705)
Foreign currency gain (loss), net	6,942	(6,927)	(27,059)	(1,688)
Loss on extinguishment of debt	(22)		(22)
Total other income	33,358	8,811	(33,183)	7,777
Income before income taxes	137,534	127,562	177,650	232,170
Income tax (provision) benefit	(3,257)	(1,832)	1,165	(1,584)
Net income	134,277	125,730	178,815	230,586
Net income attributable to Starwood Property Trust, Inc.	(4)	(21)	(7)	(392)
Net income attributable to Starwood Property Trust, Inc.	134,273	125,709	178,808	230,194
Operating segment | Infrastructure Lending Segment
Revenues:
Interest income from loans	19,126	25,291	41,539	52,206
Interest income from investment securities	683	868	1,384	1,753
Other revenues	100	7	243	693
Total revenues	19,909	26,166	43,166	54,652
Costs and expenses:
Interest expense	9,678	16,258	22,795	34,835
General and administrative	4,337	4,830	8,760	9,309
Acquisition and investment pursuit costs	1,100	14	1,117	30
Depreciation and amortization	89		159
Credit loss provision, net	(1,092)	422	7,360	1,196
Total costs and expenses	14,112	21,524	40,191	45,370
Other income (loss):
Earnings (loss) from unconsolidated entities	(1,118)		(1,118)
(Loss) gain on sale of investments and other assets, net		2,276	296	3,066
(Loss) gain on derivative financial instruments, net	(437)	(2,833)	(1,438)	(3,228)
Foreign currency gain (loss), net	310	(83)	(163)	217
Loss on extinguishment of debt		(2,816)	(170)	(6,120)
Total other income	(1,245)	(3,456)	(2,593)	(6,065)
Income before income taxes	4,552	1,186	382	3,217
Income tax (provision) benefit	(56)	186	89	271
Net income	4,496	1,372	471	3,488
Net income attributable to Starwood Property Trust, Inc.	4,496	1,372	471	3,488
Operating segment | Investing and Servicing Segment
Revenues:
Interest income from loans	1,841	3,104	4,474	5,010
Interest income from investment securities	24,924	31,163	49,724	55,456
Servicing fees	8,591	15,880	15,033	43,123
Rental income	8,454	14,971	18,561	28,283
Other revenues	280	515	793	711
Total revenues	44,090	65,633	88,585	132,583
Costs and expenses:
Management fees	220	18	459	36
Interest expense	6,177	8,515	13,371	16,261
General and administrative	14,993	20,177	35,677	39,028
Acquisition and investment pursuit costs	(88)	(100)	(68)	(23)
Costs of rental operations	3,941	6,789	8,525	13,484
Depreciation and amortization	3,749	5,191	7,956	10,478
Other expense		194		194
Total costs and expenses	28,992	40,784	65,920	79,458
Other income (loss):
Change in fair value of servicing rights	5,328	(1,159)	5,646	(1,674)
Change in fair value of investment securities, net	7,941	15,815	(39,275)	33,955
Change in fair value of mortgage loans, net	1,440	16,528	20,823	26,408
Earnings (loss) from unconsolidated entities	29,526	2,754	30,146	3,348
(Loss) gain on sale of investments and other assets, net	7,433		7,433	940
(Loss) gain on derivative financial instruments, net	(3,828)	(6,953)	(22,934)	(10,385)
Foreign currency gain (loss), net	(31)	1	(24)
Other income, net	13		89
Total other income	47,822	26,986	1,904	52,592
Income before income taxes	62,920	51,835	24,569	105,717
Income tax (provision) benefit	4,611	(1,887)	6,773	(2,296)
Net income	67,531	49,948	31,342	103,421
Net income attributable to Starwood Property Trust, Inc.	(8,166)	(117)	(3,396)	98
Net income attributable to Starwood Property Trust, Inc.	59,365	49,831	27,946	103,519
Operating segment | Property Segment
Revenues:
Rental income	63,566	72,326	127,527	142,847
Other revenues	58	88	180	166
Total revenues	63,624	72,414	127,707	143,013
Costs and expenses:
Interest expense	15,942	19,132	33,063	38,122
General and administrative	1,281	1,706	2,359	3,224
Acquisition and investment pursuit costs			12
Costs of rental operations	24,703	23,125	47,555	46,062
Depreciation and amortization	19,153	23,076	38,441	46,972
Other expense	26	1,173	337	1,307
Total costs and expenses	61,105	68,212	121,767	135,687
Other income (loss):
Earnings (loss) from unconsolidated entities		1,044		(42,761)
(Loss) gain on derivative financial instruments, net	(4,614)	(11,147)	(34,837)	(9,857)
Foreign currency gain (loss), net	(48)	(8)	(67)	1
Loss on extinguishment of debt	(2,185)		(2,185)
Other income, net	191		241
Total other income	(6,656)	(10,111)	(36,848)	(52,617)
Income before income taxes	(4,137)	(5,909)	(30,908)	(45,291)
Income tax (provision) benefit				(258)
Net income	(4,137)	(5,909)	(30,908)	(45,549)
Net income attributable to Starwood Property Trust, Inc.	(5,111)	(5,355)	(10,222)	(11,072)
Net income attributable to Starwood Property Trust, Inc.	(9,248)	(11,264)	(41,130)	(56,621)
Corporate
Revenues:
Other revenues		6		26
Total revenues		6		26
Costs and expenses:
Management fees	22,554	22,107	62,661	45,095
Interest expense	27,825	27,821	56,630	55,736
General and administrative	3,368	4,019	7,669	7,245
Total costs and expenses	53,747	53,947	126,960	108,076
Other income (loss):
(Loss) gain on derivative financial instruments, net	4,517	15,309	33,752	24,936
Loss on extinguishment of debt				6
Other income, net				(73)
Total other income	4,517	15,309	33,752	24,869
Income before income taxes	(49,230)	(38,632)	(93,208)	(83,181)
Net income	(49,230)	(38,632)	(93,208)	(83,181)
Net income attributable to Starwood Property Trust, Inc.	(49,230)	(38,632)	(93,208)	(83,181)
LNR VIEs
Revenues:
Interest income from investment securities	(28,308)	(33,853)	(57,197)	(61,307)
Servicing fees	(2,075)	(6,962)	(3,896)	(9,895)
Other revenues	(1)	(3)	(3)	(21)
Total revenues	(30,384)	(40,818)	(61,096)	(71,223)
Costs and expenses:
Management fees	2	45	33	94
Interest expense		(164)	(162)	(324)
General and administrative	83	92	167	180
Total costs and expenses	85	(27)	38	(50)
Other income (loss):
Change in net assets related to consolidated VIEs	51,261	55,158	5,768	102,994
Change in fair value of servicing rights	(7,897)	243	(8,608)	(9)
Change in fair value of investment securities, net	(12,568)	(14,200)	65,031	(30,584)
Earnings (loss) from unconsolidated entities	(303)	(473)	(877)	(1,039)
Total other income	30,493	40,728	61,314	71,362
Income before income taxes	24	(63)	180	189
Net income	24	(63)	180	189
Net income attributable to Starwood Property Trust, Inc.	$ (24)	$ 63	$ (180)	$ (189)