Segment Data - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Assets:
Cash and cash equivalents	$ 264,209	$ 217,362
Restricted cash	109,565	104,552
Loans held-for-investment, net	16,253,257	15,536,849
Loans held-for-sale	2,684,512	2,876,800
Investment securities	869,189	860,984
Properties, net	1,122,357	1,166,387
Investments in unconsolidated entities	89,250	90,097
Goodwill	259,846	259,846
Intangible assets	62,148	63,564
Derivative assets	60,869	48,216
Accrued interest receivable	123,801	116,262
Other assets	261,192	188,626
VIE assets, at fair value	57,763,543	61,280,543
Total Assets	81,187,898	83,850,397
Liabilities:
Accounts payable, accrued expenses and other liabilities	196,145	189,696
Related-party payable	56,615	76,371
Dividends payable	148,743	147,624
Derivative liabilities	38,709	13,421
Secured financing agreements, net	11,531,571	12,576,850
Collateralized loan obligations and single asset securitization, net	3,797,895	2,616,116
Unsecured senior notes, net	2,322,630	1,828,590
VIE liabilities, at fair value	56,185,937	59,752,922
Total Liabilities	74,278,245	77,201,590
Temporary Equity: Redeemable non-controlling interests	261,685	214,915
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,144	3,123
Additional paid-in capital	5,709,027	5,673,376
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income	35,669	40,953
Retained earnings (accumulated deficit)	669,877	493,106
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,279,695	6,072,536
Non-controlling interests in consolidated subsidiaries	368,273	361,356
Total Permanent Equity	6,647,968	6,433,892	$ 4,854,785	$ 4,862,576
Total Liabilities and Equity	81,187,898	83,850,397
Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,264,160	1,040,309
Total Assets	75,400
Liabilities:
Total Liabilities	30,800
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	263,625	216,772
Restricted cash	109,565	104,552
Loans held-for-investment, net	16,253,257	15,536,849
Loans held-for-sale	2,684,512	2,876,800
Investment securities	2,412,334	2,352,770
Properties, net	1,122,357	1,166,387
Investments in unconsolidated entities	104,288	105,353
Goodwill	259,846	259,846
Intangible assets	102,966	105,683
Derivative assets	60,869	48,216
Accrued interest receivable	123,942	116,393
Other assets	261,427	188,788
VIE assets, at fair value	0	0
Total Assets	25,023,148	24,118,718
Liabilities:
Accounts payable, accrued expenses and other liabilities	196,105	189,640
Related-party payable	56,615	76,371
Dividends payable	148,743	147,624
Derivative liabilities	38,709	13,421
Secured financing agreements, net	11,553,031	12,598,410
Collateralized loan obligations and single asset securitization, net	3,797,895	2,616,116
Unsecured senior notes, net	2,322,630	1,828,590
VIE liabilities, at fair value	0	0
Total Liabilities	18,113,728	17,470,172
Temporary Equity: Redeemable non-controlling interests	261,685	214,915
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,144	3,123
Additional paid-in capital	5,709,027	5,673,376
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income	35,669	40,953
Retained earnings (accumulated deficit)	669,877	493,106
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,279,695	6,072,536
Non-controlling interests in consolidated subsidiaries	368,040	361,095
Total Permanent Equity	6,647,735	6,433,631
Total Liabilities and Equity	25,023,148	24,118,718
Operating Segments and Corporate | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,264,160	1,040,309
Operating segment | Commercial and Residential Lending Segment
Assets:
Cash and cash equivalents	58,377	65,064
Restricted cash	13,142	39,853
Loans held-for-investment, net	14,107,316	13,499,520
Loans held-for-sale	2,299,153	2,590,005
Investment securities	1,207,667	1,155,452
Properties, net	104,901	124,503
Investments in unconsolidated entities	43,349	44,938
Goodwill	0	0
Intangible assets	0	0
Derivative assets	58,904	34,265
Accrued interest receivable	114,367	106,251
Other assets	135,095	68,908
VIE assets, at fair value	0	0
Total Assets	18,142,271	17,728,759
Liabilities:
Accounts payable, accrued expenses and other liabilities	102,124	57,267
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	10,990	12,870
Secured financing agreements, net	8,294,408	9,097,985
Collateralized loan obligations and single asset securitization, net	2,985,637	2,210,798
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	11,393,159	11,378,920
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,931,043	1,735,397
Treasury stock	0	0
Accumulated other comprehensive income	35,669	40,953
Retained earnings (accumulated deficit)	4,782,282	4,573,374
Total Starwood Property Trust, Inc. Stockholders’ Equity	6,748,994	6,349,724
Non-controlling interests in consolidated subsidiaries	118	115
Total Permanent Equity	6,749,112	6,349,839
Total Liabilities and Equity	18,142,271	17,728,759
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	38,762	17,011
Restricted cash	27,401	43,408
Loans held-for-investment, net	2,136,118	2,027,426
Loans held-for-sale	0	0
Investment securities	49,198	31,923
Properties, net	0	0
Investments in unconsolidated entities	27,061	26,255
Goodwill	119,409	119,409
Intangible assets	0	0
Derivative assets	161	128
Accrued interest receivable	6,274	3,207
Other assets	10,229	14,265
VIE assets, at fair value	0	0
Total Assets	2,414,613	2,283,032
Liabilities:
Accounts payable, accrued expenses and other liabilities	15,347	8,917
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	225	260
Secured financing agreements, net	924,242	1,225,548
Collateralized loan obligations and single asset securitization, net	812,258	405,318
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	0	0
Total Liabilities	1,752,072	1,640,043
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	606,871	600,412
Treasury stock	0	0
Accumulated other comprehensive income	0	0
Retained earnings (accumulated deficit)	55,670	42,577
Total Starwood Property Trust, Inc. Stockholders’ Equity	662,541	642,989
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	662,541	642,989
Total Liabilities and Equity	2,414,613	2,283,032
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	20,077	14,136
Restricted cash	950	954
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	0	0
Properties, net	880,392	887,553
Investments in unconsolidated entities	0	0
Goodwill	0	0
Intangible assets	33,292	34,619
Derivative assets	486	8
Accrued interest receivable	0	0
Other assets	59,100	43,420
VIE assets, at fair value	0	0
Total Assets	2,258,457	2,020,999
Liabilities:
Accounts payable, accrued expenses and other liabilities	11,503	14,757
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	787,977	787,396
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	799,480	802,153
Temporary Equity: Redeemable non-controlling interests	261,685	214,915
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(373,851)	(365,922)
Treasury stock	0	0
Accumulated other comprehensive income	0	0
Retained earnings (accumulated deficit)	1,362,509	1,161,334
Total Starwood Property Trust, Inc. Stockholders’ Equity	988,658	795,412
Non-controlling interests in consolidated subsidiaries	208,634	208,519
Total Permanent Equity	1,197,292	1,003,931
Total Liabilities and Equity	2,258,457	2,020,999
Operating segment | Property Segment | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	1,264,160	1,040,309
Operating segment | Investing and Servicing Segment
Assets:
Cash and cash equivalents	27,836	26,700
Restricted cash	26,371	20,337
Loans held-for-investment, net	9,823	9,903
Loans held-for-sale	385,359	286,795
Investment securities	1,155,469	1,165,395
Properties, net	137,064	154,331
Investments in unconsolidated entities	33,878	34,160
Goodwill	140,437	140,437
Intangible assets	69,674	71,064
Derivative assets	1,318	391
Accrued interest receivable	1,745	947
Other assets	33,857	40,395
VIE assets, at fair value	0	0
Total Assets	2,022,831	1,950,855
Liabilities:
Accounts payable, accrued expenses and other liabilities	32,297	58,920
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	145	291
Secured financing agreements, net	774,460	714,237
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	806,902	773,448
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	0	0
Additional paid-in capital	(388,580)	(388,196)
Treasury stock	0	0
Accumulated other comprehensive income	0	0
Retained earnings (accumulated deficit)	1,445,221	1,413,142
Total Starwood Property Trust, Inc. Stockholders’ Equity	1,056,641	1,024,946
Non-controlling interests in consolidated subsidiaries	159,288	152,461
Total Permanent Equity	1,215,929	1,177,407
Total Liabilities and Equity	2,022,831	1,950,855
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	118,573	93,861
Restricted cash	41,701	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	0	13,424
Accrued interest receivable	1,556	5,988
Other assets	23,146	21,800
VIE assets, at fair value	0	0
Total Assets	184,976	135,073
Liabilities:
Accounts payable, accrued expenses and other liabilities	34,834	49,779
Related-party payable	56,615	76,371
Dividends payable	148,743	147,624
Derivative liabilities	27,349	0
Secured financing agreements, net	771,944	773,244
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	2,322,630	1,828,590
VIE liabilities, at fair value	0	0
Total Liabilities	3,362,115	2,875,608
Temporary Equity: Redeemable non-controlling interests	0	0
Starwood Property Trust, Inc. Stockholders’ Equity:
Common stock	3,144	3,123
Additional paid-in capital	3,933,544	4,091,685
Treasury stock	(138,022)	(138,022)
Accumulated other comprehensive income	0	0
Retained earnings (accumulated deficit)	(6,975,805)	(6,697,321)
Total Starwood Property Trust, Inc. Stockholders’ Equity	(3,177,139)	(2,740,535)
Non-controlling interests in consolidated subsidiaries	0	0
Total Permanent Equity	(3,177,139)	(2,740,535)
Total Liabilities and Equity	184,976	135,073
Corporate | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	0	0
Securitization VIEs
Assets:
Cash and cash equivalents	584	590
Restricted cash	0	0
Loans held-for-investment, net	0	0
Loans held-for-sale	0	0
Investment securities	(1,543,145)	(1,491,786)
Properties, net	0	0
Investments in unconsolidated entities	(15,038)	(15,256)
Goodwill	0	0
Intangible assets	(40,818)	(42,119)
Derivative assets	0	0
Accrued interest receivable	(141)	(131)
Other assets	(235)	(162)
VIE assets, at fair value	57,763,543	61,280,543
Total Assets	56,164,750	59,731,679
Liabilities:
Accounts payable, accrued expenses and other liabilities	40	56
Related-party payable	0	0
Dividends payable	0	0
Derivative liabilities	0	0
Secured financing agreements, net	(21,460)	(21,560)
Collateralized loan obligations and single asset securitization, net	0	0
Unsecured senior notes, net	0	0
VIE liabilities, at fair value	56,185,937	59,752,922
Total Liabilities	56,164,517	59,731,418
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
Accumulated other comprehensive income	0	0
Retained earnings (accumulated deficit)	0	0
Total Starwood Property Trust, Inc. Stockholders’ Equity	0	0
Non-controlling interests in consolidated subsidiaries	233	261
Total Permanent Equity	233	261
Total Liabilities and Equity	56,164,750	59,731,679
Securitization VIEs | Primary beneficiary
Assets:
Investments of consolidated affordable housing fund, at fair value	$ 0	$ 0