Segment and Geographic Data - Balance sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Cash and cash equivalents	$ 615,522	$ 368,815	$ 255,187	$ 317,627
Restricted cash	35,233	23,069
Loans held-for-investment, net	5,847,995	5,973,079
Loans held-for-sale	63,279	203,865
Loans transferred as secured borrowings	35,000	86,573
Investment securities	807,618	724,947
Properties, net	1,944,720	919,225
Intangible assets	219,248	201,570	144,152
Investment in unconsolidated entities	204,605	199,201
Goodwill	140,437	140,437
Derivative assets	89,361	45,091
Accrued interest receivable	28,224	34,314
Other assets	101,763	102,479
VIE assets, at fair value	67,123,261	76,675,689
Total Assets	77,256,266	85,698,354
Liabilities:
Accounts payable, accrued expenses and other liabilities	198,134	156,805
Related-party payable	37,818	40,955
Dividends payable	125,075	114,947
Derivative liabilities	3,904	5,196
Secured financing agreements, net	4,154,126	3,980,699
Unsecured senior notes, net	2,011,544	1,323,795
Secured borrowings on transferred loans	35,000	88,000
VIE liabilities, at fair value	66,130,592	75,817,014
Total Liabilities	72,696,193	81,527,411
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,639	2,410
Additional paid-in capital	4,691,180	4,192,844
Treasury stock	(92,104)	(72,381)
Accumulated other comprehensive income (loss)	36,138	29,729	55,896	75,449
Retained earnings (accumulated deficit)	(115,579)	(12,286)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,522,274	4,140,316
Non-controlling interests in consolidated subsidiaries	37,799	30,627
Total Equity	4,560,073	4,170,943	$ 3,882,912	$ 4,327,133
Total Liabilities and Equity	77,256,266	85,698,354
Operating Segments and Corporate
Assets:
Cash and cash equivalents	614,374	367,837
Restricted cash	35,233	23,069
Loans held-for-investment, net	5,847,995	5,973,079
Loans held-for-sale	63,279	203,865
Loans transferred as secured borrowings	35,000	86,573
Investment securities	1,766,642	1,550,166
Properties, net	1,944,720	919,225
Intangible assets	253,486	213,399
Investment in unconsolidated entities	212,227	206,426
Goodwill	140,437	140,437
Derivative assets	89,361	45,091
Accrued interest receivable	28,224	34,314
Other assets	104,408	104,536
Total Assets	11,135,386	9,868,017
Liabilities:
Accounts payable, accrued expenses and other liabilities	197,248	156,116
Related-party payable	37,818	40,955
Dividends payable	125,075	114,947
Derivative liabilities	3,904	5,196
Secured financing agreements, net	4,177,826	3,980,699
Unsecured senior notes, net	2,011,544	1,323,795
Secured borrowings on transferred loans	35,000	88,000
Total Liabilities	6,588,415	5,709,708
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,639	2,410
Additional paid-in capital	4,691,180	4,192,844
Treasury stock	(92,104)	(72,381)
Accumulated other comprehensive income (loss)	36,138	29,729
Retained earnings (accumulated deficit)	(115,579)	(12,286)
Total Starwood Property Trust, Inc. Stockholders' Equity	4,522,274	4,140,316
Non-controlling interests in consolidated subsidiaries	24,697	17,993
Total Equity	4,546,971	4,158,309
Total Liabilities and Equity	11,135,386	9,868,017
Operating segment | Lending Segment
Assets:
Cash and cash equivalents	7,085	83,836
Restricted cash	17,885	9,775
Loans held-for-investment, net	5,827,553	5,973,079
Loans transferred as secured borrowings	35,000	86,573
Investment securities	776,072	511,966
Investment in unconsolidated entities	30,874	30,827
Derivative assets	45,282	33,412
Accrued interest receivable	25,831	34,028
Other assets	13,470	7,938
Total Assets	6,779,052	6,771,434
Liabilities:
Accounts payable, accrued expenses and other liabilities	20,769	18,822
Derivative liabilities	3,388	5,190
Secured financing agreements, net	2,258,462	2,341,897
Secured borrowings on transferred loans	35,000	88,000
Total Liabilities	2,317,619	2,453,909
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	2,218,671	2,477,987
Accumulated other comprehensive income (loss)	44,903	37,242
Retained earnings (accumulated deficit)	2,186,727	1,790,705
Total Starwood Property Trust, Inc. Stockholders' Equity	4,450,301	4,305,934
Non-controlling interests in consolidated subsidiaries	11,132	11,591
Total Equity	4,461,433	4,317,525
Total Liabilities and Equity	6,779,052	6,771,434
Operating segment | Investment and Servicing Segment
Assets:
Cash and cash equivalents	38,798	62,649
Restricted cash	8,202	8,826
Loans held-for-investment, net	20,442
Loans held-for-sale	63,279	203,865
Investment securities	990,570	1,038,200
Properties, net	277,612	150,497
Intangible assets	125,327	152,278
Investment in unconsolidated entities	56,376	53,145
Goodwill	140,437	140,437
Derivative assets	1,186	2,087
Accrued interest receivable	2,393	286
Other assets	59,503	71,505
Total Assets	1,784,125	1,883,775
Liabilities:
Accounts payable, accrued expenses and other liabilities	68,603	90,399
Related-party payable	440	423
Derivative liabilities	516	6
Secured financing agreements, net	426,683	422,260
Total Liabilities	496,242	513,088
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	883,761	1,146,926
Accumulated other comprehensive income (loss)	(437)	(3,714)
Retained earnings (accumulated deficit)	390,994	221,073
Total Starwood Property Trust, Inc. Stockholders' Equity	1,274,318	1,364,285
Non-controlling interests in consolidated subsidiaries	13,565	6,402
Total Equity	1,287,883	1,370,687
Total Liabilities and Equity	1,784,125	1,883,775
Operating segment | Property Segment
Assets:
Cash and cash equivalents	7,701	2,944
Restricted cash	9,146	4,468
Properties, net	1,667,108	768,728
Intangible assets	128,159	61,121
Investment in unconsolidated entities	124,977	122,454
Derivative assets	42,893	9,592
Other assets	29,569	23,657
Total Assets	2,009,553	992,964
Liabilities:
Accounts payable, accrued expenses and other liabilities	81,873	25,427
Secured financing agreements, net	1,196,830	568,738
Total Liabilities	1,278,703	594,165
Starwood Property Trust, Inc. Stockholders' Equity:
Additional paid-in capital	696,049	394,465
Accumulated other comprehensive income (loss)	(8,328)	(3,799)
Retained earnings (accumulated deficit)	43,129	8,133
Total Starwood Property Trust, Inc. Stockholders' Equity	730,850	398,799
Total Equity	730,850	398,799
Total Liabilities and Equity	2,009,553	992,964
Corporate
Assets:
Cash and cash equivalents	560,790	218,408
Other assets	1,866	1,436
Total Assets	562,656	219,844
Liabilities:
Accounts payable, accrued expenses and other liabilities	26,003	21,468
Related-party payable	37,378	40,532
Dividends payable	125,075	114,947
Secured financing agreements, net	295,851	647,804
Unsecured senior notes, net	2,011,544	1,323,795
Total Liabilities	2,495,851	2,148,546
Starwood Property Trust, Inc. Stockholders' Equity:
Common stock	2,639	2,410
Additional paid-in capital	892,699	173,466
Treasury stock	(92,104)	(72,381)
Retained earnings (accumulated deficit)	(2,736,429)	(2,032,197)
Total Starwood Property Trust, Inc. Stockholders' Equity	(1,933,195)	(1,928,702)
Total Equity	(1,933,195)	(1,928,702)
Total Liabilities and Equity	562,656	219,844
Investment and Servicing VIEs
Assets:
Cash and cash equivalents	1,148	978
Investment securities	(959,024)	(825,219)
Intangible assets	(34,238)	(11,829)
Investment in unconsolidated entities	(7,622)	(7,225)
Other assets	(2,645)	(2,057)
VIE assets, at fair value	67,123,261	76,675,689
Total Assets	66,120,880	75,830,337
Liabilities:
Accounts payable, accrued expenses and other liabilities	886	689
Secured financing agreements, net	(23,700)
VIE liabilities, at fair value	66,130,592	75,817,014
Total Liabilities	66,107,778	75,817,703
Starwood Property Trust, Inc. Stockholders' Equity:
Non-controlling interests in consolidated subsidiaries	13,102	12,634
Total Equity	13,102	12,634
Total Liabilities and Equity	$ 66,120,880	$ 75,830,337