Segment and Geographic Data - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Cash and cash equivalents	$ 217,362	$ 563,217
Restricted cash	104,552	158,945
Loans held-for-investment, net	15,536,849	11,087,073
Loans held-for-sale	2,876,800	1,052,835
Investment securities	860,984	736,658
Properties, net	1,166,387	2,271,153
Investments in unconsolidated entities	90,097	108,054
Goodwill	259,846	259,846
Intangible assets	63,564	70,117	$ 85,700
Derivative assets	48,216	40,555
Accrued interest receivable	116,262	95,980
Other assets	188,626	190,748
VIE assets, at fair value	61,280,543	64,238,328
Total Assets	83,850,397	80,873,509
Liabilities:
Accounts payable, accrued expenses and other liabilities	189,696	206,845
Related-party payable	76,371	39,170
Dividends payable	147,624	137,959
Derivative liabilities	13,421	41,324
Secured financing agreements, net	12,576,850	10,146,190
Collateralized loan obligations and single asset securitization, net	2,616,116	930,554
Unsecured senior notes, net	1,828,590	1,732,520
VIE liabilities, at fair value	59,752,922	62,776,371
Total Liabilities	77,201,590	76,010,933
Temporary Equity: Redeemable non-controlling interests	214,915	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,123	2,921
Additional paid-in capital	5,673,376	5,209,739
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income (loss)	40,953	43,993
Retained earnings (accumulated deficit)	493,106	(629,733)
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,072,536	4,488,898
Non-controlling interests in consolidated subsidiaries	361,356	373,678
Total Permanent Equity	6,433,892	4,862,576	$ 5,137,014	$ 4,900,189
Total Liabilities and Equity	83,850,397	80,873,509
Primary beneficiary
Assets:
Investments, fair value	1,040,309	0
Total Assets	102,400
Liabilities:
Total Liabilities	53,500
Infrastructure Lending Segment
Assets:
Goodwill	119,400	119,400
Investing and Servicing Segment
Assets:
Goodwill	140,400	140,400
Operating Segments and Corporate
Assets:
Cash and cash equivalents	216,772	562,445
Restricted cash	104,552	158,945
Loans held-for-investment, net	15,536,849	11,087,073
Loans held-for-sale	2,876,800	1,052,835
Investment securities	2,352,770	2,162,228
Properties, net	1,166,387	2,271,153
Investments in unconsolidated entities	105,353	124,166
Goodwill	259,846	259,846
Intangible assets	105,683	111,493
Derivative assets	48,216	40,555
Accrued interest receivable	116,393	96,114
Other assets	188,788	190,755
VIE assets, at fair value	0	0
Total Assets	24,118,718	18,117,608
Liabilities:
Accounts payable, accrued expenses and other liabilities	189,640	206,770
Related-party payable	76,371	39,170
Dividends payable	147,624	137,959
Derivative liabilities	13,421	41,324
Secured financing agreements, net	12,598,410	10,168,190
Collateralized loan obligations and single asset securitization, net	2,616,116	930,554
Unsecured senior notes, net	1,828,590	1,732,520
VIE liabilities, at fair value	0	0
Total Liabilities	17,470,172	13,256,487
Temporary Equity: Redeemable non-controlling interests	214,915
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,123	2,921
Additional paid-in capital	5,673,376	5,209,739
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income (loss)	40,953	43,993
Retained earnings (accumulated deficit)	493,106	(629,733)
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,072,536	4,488,898
Non-controlling interests in consolidated subsidiaries	361,095	372,223
Total Permanent Equity	6,433,631	4,861,121
Total Liabilities and Equity	24,118,718	18,117,608
Operating Segments and Corporate | Primary beneficiary
Assets:
Investments, fair value	1,040,309
Operating segment | Commercial and Residential Lending Segment
Assets:
Cash and cash equivalents	65,064	160,007
Restricted cash	39,853	93,445
Loans held-for-investment, net	13,499,520	9,673,625
Loans held-for-sale	2,590,005	841,963
Investment securities	1,155,452	1,014,402
Properties, net	124,503	103,896
Investments in unconsolidated entities	44,938	54,407
Goodwill	0	0
Intangible assets	0	0
Derivative assets	34,265	6,595
Accrued interest receivable	106,251	87,922
Other assets	68,908	61,638
VIE assets, at fair value	0	0
Total Assets	17,728,759	12,097,900
Liabilities:
Accounts payable, accrued expenses and other liabilities	57,267	41,104
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	12,870	39,082
Secured financing agreements, net	9,097,985	5,893,999
Collateralized loan obligations and single asset securitization, net	2,210,798	930,554
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	11,378,920	6,904,739
Temporary Equity: Redeemable non-controlling interests	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,735,397	1,192,584
Treasury stock	0	0
Accumulated other comprehensive income (loss)	40,953	44,057
Retained earnings (accumulated deficit)	4,573,374	3,956,405
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,349,724	5,193,046
Non-controlling interests in consolidated subsidiaries	115	115
Total Permanent Equity	6,349,839	5,193,161
Total Liabilities and Equity	17,728,759	12,097,900
Operating segment | Commercial and Residential Lending Segment | Primary beneficiary
Assets:
Investments, fair value	0
Operating segment | Infrastructure Lending Segment
Assets:
Cash and cash equivalents	17,011	4,440
Restricted cash	43,408	45,113
Loans held-for-investment, net	2,027,426	1,412,440
Loans held-for-sale	0	120,540
Investment securities	31,923	35,681
Properties, net	0	0
Investments in unconsolidated entities	26,255	25,095
Goodwill	119,409	119,409
Intangible assets	0	0
Derivative assets	128	0
Accrued interest receivable	3,207	2,091
Other assets	14,265	4,531
VIE assets, at fair value	0	0
Total Assets	2,283,032	1,769,340
Liabilities:
Accounts payable, accrued expenses and other liabilities	8,917	12,144
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	260	1,718
Secured financing agreements, net	1,225,548	1,240,763
Collateralized loan obligations and single asset securitization, net	405,318	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	1,640,043	1,254,625
Temporary Equity: Redeemable non-controlling interests	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	600,412	496,387
Treasury stock	0	0
Accumulated other comprehensive income (loss)	0	0
Retained earnings (accumulated deficit)	42,577	18,328
Total Starwood Property Trust, Inc. Stockholders’ Equity	642,989	514,715
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	642,989	514,715
Total Liabilities and Equity	2,283,032	1,769,340
Operating segment | Infrastructure Lending Segment | Primary beneficiary
Assets:
Investments, fair value	0
Operating segment | Property Segment
Assets:
Cash and cash equivalents	14,136	32,080
Restricted cash	954	7,192
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	0	0
Properties, net	887,553	1,969,414
Investments in unconsolidated entities	0	0
Goodwill	0	0
Intangible assets	34,619	40,370
Derivative assets	8	41
Accrued interest receivable	0	0
Other assets	43,420	69,859
VIE assets, at fair value	0	0
Total Assets	2,020,999	2,118,956
Liabilities:
Accounts payable, accrued expenses and other liabilities	14,757	43,630
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	787,396	1,794,609
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	802,153	1,838,239
Temporary Equity: Redeemable non-controlling interests	214,915
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(365,922)	98,882
Treasury stock	0	0
Accumulated other comprehensive income (loss)	0	0
Retained earnings (accumulated deficit)	1,161,334	(44,832)
Total Starwood Property Trust, Inc. Stockholders’ Equity	795,412	54,050
Non-controlling interests in consolidated subsidiaries	208,519	226,667
Total Permanent Equity	1,003,931	280,717
Total Liabilities and Equity	2,020,999	2,118,956
Operating segment | Property Segment | Primary beneficiary
Assets:
Investments, fair value	1,040,309
Operating segment | Investing and Servicing Segment
Assets:
Cash and cash equivalents	26,700	19,546
Restricted cash	20,337	13,195
Loans held-for-investment, net	9,903	1,008
Loans held-for-sale	286,795	90,332
Investment securities	1,165,395	1,112,145
Properties, net	154,331	197,843
Investments in unconsolidated entities	34,160	44,664
Goodwill	140,437	140,437
Intangible assets	71,064	71,123
Derivative assets	391	147
Accrued interest receivable	947	123
Other assets	40,395	44,579
VIE assets, at fair value	0	0
Total Assets	1,950,855	1,735,142
Liabilities:
Accounts payable, accrued expenses and other liabilities	58,920	45,309
Related-party payable	0	5
Dividends payable	0	0
Derivative liabilities	291	524
Secured financing agreements, net	714,237	606,100
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	773,448	651,938
Temporary Equity: Redeemable non-controlling interests	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(388,196)	(322,992)
Treasury stock	0	0
Accumulated other comprehensive income (loss)	0	(64)
Retained earnings (accumulated deficit)	1,413,142	1,260,819
Total Starwood Property Trust, Inc. Stockholders’ Equity	1,024,946	937,763
Non-controlling interests in consolidated subsidiaries	152,461	145,441
Total Permanent Equity	1,177,407	1,083,204
Total Liabilities and Equity	1,950,855	1,735,142
Operating segment | Investing and Servicing Segment | Primary beneficiary
Assets:
Investments, fair value	0
Corporate
Assets:
Cash and cash equivalents	93,861	346,372
Restricted cash	0	0
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	0	0
Properties, net	0	0
Investments in unconsolidated entities	0	0
Goodwill	0	0
Intangible assets	0	0
Derivative assets	13,424	33,772
Accrued interest receivable	5,988	5,978
Other assets	21,800	10,148
VIE assets, at fair value	0	0
Total Assets	135,073	396,270
Liabilities:
Accounts payable, accrued expenses and other liabilities	49,779	64,583
Related-party payable	76,371	39,165
Dividends payable	147,624	137,959
Derivative liabilities	0	0
Secured financing agreements, net	773,244	632,719
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	1,828,590	1,732,520
VIE liabilities, at fair value	0	0
Total Liabilities	2,875,608	2,606,946
Temporary Equity: Redeemable non-controlling interests	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,123	2,921
Additional paid-in capital	4,091,685	3,744,878
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income (loss)	0	0
Retained earnings (accumulated deficit)	(6,697,321)	(5,820,453)
Total Starwood Property Trust, Inc. Stockholders’ Equity	(2,740,535)	(2,210,676)
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	(2,740,535)	(2,210,676)
Total Liabilities and Equity	135,073	396,270
Corporate | Primary beneficiary
Assets:
Investments, fair value	0
Securitization VIEs
Assets:
Cash and cash equivalents	590	772
Restricted cash	0	0
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	(1,491,786)	(1,425,570)
Properties, net	0	0
Investments in unconsolidated entities	(15,256)	(16,112)
Goodwill	0	0
Intangible assets	(42,119)	(41,376)
Derivative assets	0	0
Accrued interest receivable	(131)	(134)
Other assets	(162)	(7)
VIE assets, at fair value	61,280,543	64,238,328
Total Assets	59,731,679	62,755,901
Liabilities:
Accounts payable, accrued expenses and other liabilities	56	75
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	(21,560)	(22,000)
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	59,752,922	62,776,371
Total Liabilities	59,731,418	62,754,446
Temporary Equity: Redeemable non-controlling interests	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	0	0
Treasury stock	0	0
Accumulated other comprehensive income (loss)	0	0
Retained earnings (accumulated deficit)	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	0	0
Non-controlling interests in consolidated subsidiaries	261	1,455
Total Permanent Equity	261	1,455
Total Liabilities and Equity	59,731,679	$ 62,755,901
Securitization VIEs | Primary beneficiary
Assets:
Investments, fair value	$ 0