Segment Data - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Assets:
Cash and cash equivalents	$ 395,799	$ 261,061
Restricted cash	135,637	121,072
Loans held-for-investment, net	18,452,424	18,401,439
Loans held-for-sale	2,810,889	2,784,594
Investment securities	772,887	815,804
Properties, net	1,443,979	1,449,986
Investments in unconsolidated entities	93,069	91,892
Goodwill	259,846	259,846
Intangible assets	66,796	68,773
Derivative assets	96,619	108,621
Accrued interest receivable	181,807	168,521
Other assets	356,076	297,477
VIE assets, at fair value	50,526,390	52,453,041
Total Assets	77,354,380	79,043,129
Liabilities:
Accounts Payable and Accrued Liabilities	277,330	298,999
Related-party payable	39,583	41,186
Dividends payable	152,267	151,511
Derivative liabilities	78,407	91,404
Secured financing agreements, net	14,846,988	14,501,532
Collateralized loan obligations and single asset securitization, net	3,672,783	3,676,224
Unsecured senior notes, net	2,331,445	2,329,211
VIE liabilities, at fair value	48,838,686	50,754,355
Total Liabilities	70,237,489	71,844,422
Temporary Equity: Redeemable non-controlling interests	364,418	362,790
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,197	3,181
Additional paid-in capital	5,826,509	5,807,087
Treasury stock	(138,022)	(138,022)
Retained earnings (accumulated deficit)	670,690	769,237
Accumulated other comprehensive income	19,851	20,955
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,382,225	6,462,438
Non-controlling interests in consolidated subsidiaries	370,248	373,479
Total Permanent Equity	6,752,473	6,835,917	$ 6,647,968	$ 6,433,892
Total Liabilities and Equity	77,354,380	79,043,129
Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,762,162	1,761,002
Total Assets	75,400
Liabilities:
Total Liabilities	35,300
Infrastructure Lending Segment
Assets:
Goodwill	119,400	119,400
Investing and Servicing Segment
Assets:
Goodwill	140,400	140,400
Subtotal
Assets:
Cash and cash equivalents	395,799	261,061
Restricted cash	135,637	121,072
Loans held-for-investment, net	18,452,424	18,401,439
Loans held-for-sale	2,810,889	2,784,594
Investment securities	2,428,723	2,482,725
Properties, net	1,443,979	1,449,986
Investments in unconsolidated entities	106,952	105,434
Goodwill	259,846	259,846
Intangible assets	105,500	107,831
Derivative assets	96,619	108,621
Accrued interest receivable	182,095	168,796
Other assets	356,076	297,477
VIE assets, at fair value	0	0
Total Assets	28,536,701	28,309,884
Liabilities:
Accounts Payable and Accrued Liabilities	277,330	298,999
Related-party payable	39,583	41,186
Dividends payable	152,267	151,511
Derivative liabilities	78,407	91,404
Secured financing agreements, net	14,868,050	14,522,698
Collateralized loan obligations and single asset securitization, net	3,672,783	3,676,224
Unsecured senior notes, net	2,331,445	2,329,211
VIE liabilities, at fair value	0	0
Total Liabilities	21,419,865	21,111,233
Temporary Equity: Redeemable non-controlling interests	364,418	362,790
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,197	3,181
Additional paid-in capital	5,826,509	5,807,087
Treasury stock	(138,022)	(138,022)
Retained earnings (accumulated deficit)	670,690	769,237
Accumulated other comprehensive income	19,851	20,955
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,382,225	6,462,438
Non-controlling interests in consolidated subsidiaries	370,193	373,423
Total Permanent Equity	6,752,418	6,835,861
Total Liabilities and Equity	28,536,701	28,309,884
Subtotal | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,762,162	1,761,002
Operating segment | Commercial and Residential Lending Segment
Assets:
Cash and cash equivalents	13,903	68,593
Restricted cash	9,872	18,556
Loans held-for-investment, net	16,085,101	16,038,930
Loans held-for-sale	2,733,358	2,763,458
Investment securities	1,257,966	1,250,893
Properties, net	464,183	463,492
Investments in unconsolidated entities	24,955	25,326
Goodwill	0	0
Intangible assets	11,273	11,908
Derivative assets	90,967	101,082
Accrued interest receivable	171,304	151,852
Other assets	218,197	170,177
VIE assets, at fair value	0	0
Total Assets	21,081,079	21,064,267
Liabilities:
Accounts Payable and Accrued Liabilities	154,121	146,897
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	21,283	21,523
Secured financing agreements, net	11,097,202	10,804,970
Collateralized loan obligations and single asset securitization, net	2,858,185	2,862,211
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	14,130,791	13,835,601
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,702,444	2,124,496
Treasury stock	0	0
Retained earnings (accumulated deficit)	5,227,875	5,083,100
Accumulated other comprehensive income	19,851	20,955
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,950,170	7,228,551
Non-controlling interests in consolidated subsidiaries	118	115
Total Permanent Equity	6,950,288	7,228,666
Total Liabilities and Equity	21,081,079	21,064,267
Operating segment | Commercial and Residential Lending Segment | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	0	0
Operating segment | Infrastructure Lending Segment
Assets:
Cash and cash equivalents	30,948	31,153
Restricted cash	33,848	31,133
Loans held-for-investment, net	2,357,831	2,352,932
Loans held-for-sale	0	0
Investment securities	20,841	66,204
Properties, net	0	0
Investments in unconsolidated entities	48,819	47,078
Goodwill	119,409	119,409
Intangible assets	0	0
Derivative assets	219	122
Accrued interest receivable	8,408	9,856
Other assets	3,658	3,614
VIE assets, at fair value	0	0
Total Assets	2,623,981	2,661,501
Liabilities:
Accounts Payable and Accrued Liabilities	19,433	20,656
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	146	105
Secured financing agreements, net	1,048,486	1,042,679
Collateralized loan obligations and single asset securitization, net	814,598	814,013
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	1,882,663	1,877,453
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	631,627	683,258
Treasury stock	0	0
Retained earnings (accumulated deficit)	109,691	100,790
Accumulated other comprehensive income	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	741,318	784,048
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	741,318	784,048
Total Liabilities and Equity	2,623,981	2,661,501
Operating segment | Infrastructure Lending Segment | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	0	0
Operating segment | Property Segment
Assets:
Cash and cash equivalents	27,742	31,194
Restricted cash	943	981
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	0	0
Properties, net	860,220	864,778
Investments in unconsolidated entities	0	0
Goodwill	0	0
Intangible assets	28,442	29,613
Derivative assets	3,025	1,803
Accrued interest receivable	967	863
Other assets	57,323	54,313
VIE assets, at fair value	0	0
Total Assets	2,740,824	2,744,547
Liabilities:
Accounts Payable and Accrued Liabilities	13,601	11,716
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	790,299	789,719
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	803,900	801,435
Temporary Equity: Redeemable non-controlling interests	364,418	362,790
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(415,147)	(405,955)
Treasury stock	0	0
Retained earnings (accumulated deficit)	1,779,019	1,777,643
Accumulated other comprehensive income	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	1,363,872	1,371,688
Non-controlling interests in consolidated subsidiaries	208,634	208,634
Total Permanent Equity	1,572,506	1,580,322
Total Liabilities and Equity	2,740,824	2,744,547
Operating segment | Property Segment | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,762,162	1,761,002
Operating segment | Investing and Servicing Segment
Assets:
Cash and cash equivalents	16,910	39,023
Restricted cash	4,632	5,259
Loans held-for-investment, net	9,492	9,577
Loans held-for-sale	77,531	21,136
Investment securities	1,149,916	1,165,628
Properties, net	119,576	121,716
Investments in unconsolidated entities	33,178	33,030
Goodwill	140,437	140,437
Intangible assets	65,785	66,310
Derivative assets	2,408	5,614
Accrued interest receivable	1,356	1,105
Other assets	20,850	12,929
VIE assets, at fair value	0	0
Total Assets	1,642,071	1,621,764
Liabilities:
Accounts Payable and Accrued Liabilities	23,093	46,377
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	591,279	543,256
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	614,372	589,633
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(639,082)	(646,662)
Treasury stock	0	0
Retained earnings (accumulated deficit)	1,505,340	1,514,119
Accumulated other comprehensive income	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	866,258	867,457
Non-controlling interests in consolidated subsidiaries	161,441	164,674
Total Permanent Equity	1,027,699	1,032,131
Total Liabilities and Equity	1,642,071	1,621,764
Operating segment | Investing and Servicing Segment | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	0	0
Corporate
Assets:
Cash and cash equivalents	306,296	91,098
Restricted cash	86,342	65,143
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	0	0
Accrued interest receivable	60	5,120
Other assets	56,048	56,444
VIE assets, at fair value	0	0
Total Assets	448,746	217,805
Liabilities:
Accounts Payable and Accrued Liabilities	67,082	73,353
Related-party payable	39,583	41,186
Dividends payable	152,267	151,511
Derivative liabilities	56,978	69,776
Secured financing agreements, net	1,340,784	1,342,074
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	2,331,445	2,329,211
VIE liabilities, at fair value	0	0
Total Liabilities	3,988,139	4,007,111
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,197	3,181
Additional paid-in capital	4,546,667	4,051,950
Treasury stock	(138,022)	(138,022)
Retained earnings (accumulated deficit)	(7,951,235)	(7,706,415)
Accumulated other comprehensive income	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	(3,539,393)	(3,789,306)
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	(3,539,393)	(3,789,306)
Total Liabilities and Equity	448,746	217,805
Corporate | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	0	0
Securitization VIEs
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	(1,655,836)	(1,666,921)
Properties, net	0	0
Investments in unconsolidated entities	(13,883)	(13,542)
Goodwill	0	0
Intangible assets	(38,704)	(39,058)
Derivative assets	0	0
Accrued interest receivable	(288)	(275)
Other assets	0	0
VIE assets, at fair value	50,526,390	52,453,041
Total Assets	48,817,679	50,733,245
Liabilities:
Accounts Payable and Accrued Liabilities	0	0
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	(21,062)	(21,166)
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	48,838,686	50,754,355
Total Liabilities	48,817,624	50,733,189
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	0	0
Treasury stock	0	0
Retained earnings (accumulated deficit)	0	0
Accumulated other comprehensive income	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	0	0
Non-controlling interests in consolidated subsidiaries	55	56
Total Permanent Equity	55	56
Total Liabilities and Equity	48,817,679	50,733,245
Securitization VIEs | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	$ 0	$ 0