Condensed Consolidated Statements of Equity $ in Thousands	USD ($) shares	Cumulative Effect, Period of Adoption, Adjustment USD ($)	Total Starwood Property Trust, Inc. Stockholders’ Equity USD ($)	Total Starwood Property Trust, Inc. Stockholders’ Equity Cumulative Effect, Period of Adoption, Adjustment USD ($)	Common stock USD ($) shares	Additional Paid-in Capital USD ($)	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment USD ($)	Treasury Stock​ USD ($) shares	Accumulated Deficit USD ($)	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment USD ($)	Accumulated Other Comprehensive Income USD ($)	Non- Controlling Interests USD ($)
Beginning Balance (in shares) at Dec. 31, 2019 | shares					287,380,891			5,180,140
Beginning Balance at Dec. 31, 2019	$ 5,137,014	$ (32,286)	$ 4,700,425	$ (32,286)	$ 2,874	$ 5,132,532		$ (104,194)	$ (381,719)	$ (32,286)	$ 50,932	$ 436,589
Increase (Decrease) in Stockholders' Equity
Proceeds from DRIP Plan (in shares) | shares					59,340
Proceeds from DRIP Plan	890		890		$ 1	889
Redemption of Class A Units (in shares)					409,712
Redemption of Class A Units	(1,285)		8,956		$ 4	8,952						(10,241)
Equity offering costs	(69)		(69)			(69)
Common stock repurchased (in shares) | shares								1,925,421
Common stock repurchased	(28,830)		(28,830)					$ (28,830)
Share-based compensation (in shares) | shares					1,516,152
Share-based compensation	22,405		22,405		$ 15	22,390
Manager fee paid in stock (in shares) | shares					2,421,232
Manager fees paid in stock	36,046		36,046		$ 24	36,022
Net income	251,426		224,721						224,721			26,705
Dividends declared	(409,730)		(409,730)						(409,730)
Other comprehensive loss, net	(8,647)		(8,647)								(8,647)
VIE non-controlling interests	(2,177)											(2,177)
Contributions from non-controlling interests	9,657											9,657
Distributions to non-controlling interests	(88,721)											(88,721)
Ending Balance (in shares) at Sep. 30, 2020 | shares					291,787,327			7,105,561
Ending Balance at Sep. 30, 2020	$ 4,885,693		4,513,881		$ 2,918	5,200,716		$ (133,024)	(599,014)		42,285	371,812
Accounting Standards Update [Extensible List]	stwd:AccountingStandardsUpdate202006Member
Beginning Balance (in shares) at Dec. 31, 2019 | shares					287,380,891			5,180,140
Beginning Balance at Dec. 31, 2019	$ 5,137,014	(32,286)	4,700,425	(32,286)	$ 2,874	5,132,532		$ (104,194)	(381,719)	(32,286)	50,932	436,589
Ending Balance (in shares) at Dec. 31, 2020 | shares	292,091,601				292,091,601			7,448,691
Ending Balance at Dec. 31, 2020	$ 4,862,576	(1,536)	4,488,898	(1,536)	$ 2,921	5,209,739	$ (3,755)	$ (138,022)	(629,733)	2,219	43,993	373,678
Beginning Balance (in shares) at Jun. 30, 2020 | shares					291,573,083			7,105,561
Beginning Balance at Jun. 30, 2020	4,864,796		4,492,237		$ 2,916	5,193,572		$ (133,024)	(614,093)		42,866	372,559
Increase (Decrease) in Stockholders' Equity
Proceeds from DRIP Plan (in shares) | shares					34,309
Proceeds from DRIP Plan	521		521		$ 1	520
Redemption of Class A Units	(1,285)		418			418						(1,703)
Equity offering costs	(54)		(54)			(54)
Share-based compensation (in shares) | shares					179,935
Share-based compensation	6,261		6,261		$ 1	6,260
Net income	164,734		151,834						151,834			12,900
Dividends declared	(136,755)		(136,755)						(136,755)
Other comprehensive loss, net	(581)		(581)								(581)
VIE non-controlling interests	12											12
Contributions from non-controlling interests	251											251
Distributions to non-controlling interests	(12,207)											(12,207)
Ending Balance (in shares) at Sep. 30, 2020 | shares					291,787,327			7,105,561
Ending Balance at Sep. 30, 2020	$ 4,885,693		4,513,881		$ 2,918	5,200,716		$ (133,024)	(599,014)		42,285	371,812
Beginning Balance (in shares) at Dec. 31, 2020 | shares	292,091,601				292,091,601			7,448,691
Beginning Balance at Dec. 31, 2020	$ 4,862,576	$ (1,536)	4,488,898	$ (1,536)	$ 2,921	5,209,739	$ (3,755)	$ (138,022)	(629,733)	$ 2,219	43,993	373,678
Increase (Decrease) in Stockholders' Equity
Proceeds from DRIP Plan (in shares) | shares					29,331
Proceeds from DRIP Plan	697		697			697
Redemption of Class A Units (in shares)					853,681
Redemption of Class A Units	0		17,738		$ 9	17,729						(17,738)
Equity offering costs	(27)		(27)			(27)
Share-based compensation (in shares) | shares					2,400,946
Share-based compensation	29,359		29,359		$ 24	29,335
Manager fee paid in stock (in shares) | shares					696,531
Manager fees paid in stock	16,554		16,554		$ 7	16,547
Net income	389,397		356,290						356,290			33,107
Dividends declared	(416,756)		(416,756)						(416,756)
Other comprehensive loss, net	(3,507)		(3,507)								(3,507)
Contributions from non-controlling interests	5,590											5,590
Distributions to non-controlling interests	$ (35,235)											(35,235)
Ending Balance (in shares) at Sep. 30, 2021 | shares	296,072,090				296,072,090			7,448,691
Ending Balance at Sep. 30, 2021	$ 4,847,112		4,487,710		$ 2,961	5,270,265		$ (138,022)	(687,980)		40,486	359,402
Beginning Balance (in shares) at Jun. 30, 2021 | shares					295,257,898			7,448,691
Beginning Balance at Jun. 30, 2021	4,851,700		4,477,355		$ 2,952	5,248,490		$ (138,022)	(677,375)		41,310	374,345
Increase (Decrease) in Stockholders' Equity
Proceeds from DRIP Plan (in shares) | shares					8,161
Proceeds from DRIP Plan	209		209			209
Redemption of Class A Units (in shares)					465,679
Redemption of Class A Units	0		9,622		$ 5	9,617						(9,622)
Equity offering costs	(5)		(5)			(5)
Share-based compensation (in shares) | shares					243,201
Share-based compensation	9,452		9,452		$ 3	9,449
Manager fee paid in stock (in shares) | shares					97,151
Manager fees paid in stock	2,506		2,506		$ 1	2,505
Net income	140,487		128,602						128,602			11,885
Dividends declared	(139,207)		(139,207)						(139,207)
Other comprehensive loss, net	(824)		(824)								(824)
Contributions from non-controlling interests	52											52
Distributions to non-controlling interests	$ (17,258)											(17,258)
Ending Balance (in shares) at Sep. 30, 2021 | shares	296,072,090				296,072,090			7,448,691
Ending Balance at Sep. 30, 2021	$ 4,847,112		$ 4,487,710		$ 2,961	$ 5,270,265		$ (138,022)	$ (687,980)		$ 40,486	$ 359,402