Secured Borrowings - Collateralized Loan Obligations (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($) Item	Dec. 31, 2021 USD ($) Item	Feb. 28, 2022 USD ($)	Jan. 31, 2022 USD ($)	May 31, 2021 USD ($)	Apr. 30, 2021 USD ($)	Aug. 31, 2019 USD ($)
Summary of CLO
Carrying value	$ 3,797,895	$ 2,616,116
Collateral assets
Summary of CLO
Amount issued	4,471,652	3,086,319
Carrying value	4,564,657	3,120,444
Financing
Summary of CLO
Amount issued	3,815,191	2,633,841
Carrying value	$ 3,797,895	$ 2,616,116
STWD 2022-FL3
Summary of CLO
Amount issued			$ 1,000,000
STWD 2022-FL3 | Collateral assets
Summary of CLO
Count | Item	24
Amount issued	$ 1,000,000
Carrying value	$ 1,011,426
STWD 2022-FL3 | Financing
Summary of CLO
Count | Item	1
Amount issued	$ 842,500
Carrying value	$ 844,461
STWD 2022-FL3 | SOFR | Collateral assets
Summary of CLO
Spread	3.61%
STWD 2022-FL3 | SOFR | Financing
Summary of CLO
Spread	1.91%
STWD 2021-HTS | Collateral assets
Summary of CLO
Count | Item	1	1
Amount issued	$ 230,000	$ 230,000
Carrying value	$ 230,609	$ 230,587
STWD 2021-HTS | Financing
Summary of CLO
Count | Item	1	1
Amount issued	$ 210,091	$ 210,091
Carrying value	$ 208,283	$ 208,057
STWD 2021-HTS | LIBOR | Collateral assets
Summary of CLO
Spread	3.89%	4.12%
STWD 2021-HTS | LIBOR | Financing
Summary of CLO
Spread	2.69%	2.48%
STWD 2021-FL2
Summary of CLO
Amount issued					$ 1,300,000
Percent of outstanding loan	7.00%
Debt, weighted average interest rate	7.55%
STWD 2021-FL2 | Collateral assets
Summary of CLO
Count | Item	25	25
Amount issued	$ 1,276,181	$ 1,272,133
Carrying value	$ 1,280,262	$ 1,279,678
STWD 2021-FL2 | Financing
Summary of CLO
Count | Item	1	1
Amount issued	$ 1,077,375	$ 1,077,375
Carrying value	$ 1,070,369	$ 1,069,691
STWD 2021-FL2 | LIBOR | Collateral assets
Summary of CLO
Spread	4.19%	4.22%
STWD 2021-FL2 | LIBOR | Financing
Summary of CLO
Spread	1.78%	1.78%
STWD 2019-FL1
Summary of CLO
Amount issued							$ 1,100,000
STWD 2019-FL1 | Collateral assets
Summary of CLO
Count | Item	19	24
Amount issued	$ 999,432	$ 1,092,887
Carrying value	$ 1,031,438	$ 1,103,513
STWD 2019-FL1 | Financing
Summary of CLO
Count | Item	1	1
Amount issued	$ 865,225	$ 936,375
Carrying value	$ 862,524	$ 933,049
STWD 2019-FL1 | LIBOR | Collateral assets
Summary of CLO
Spread	4.08%	4.19%
STWD 2019-FL1 | SOFR | Financing
Summary of CLO
Spread	1.64%	1.63%
STWD 2021-SIF2
Summary of CLO
Amount issued				$ 500,000
Percent of outstanding loan	3.00%
Debt, weighted average interest rate	7.75%
STWD 2021-SIF2 | Collateral assets
Summary of CLO
Count | Item	34
Amount issued	$ 482,796
Carrying value	$ 504,479
STWD 2021-SIF2 | Financing
Summary of CLO
Count | Item	1
Amount issued	$ 410,000
Carrying value	$ 406,581
STWD 2021-SIF2 | SOFR | Collateral assets
Summary of CLO
Spread	3.72%
STWD 2021-SIF2 | SOFR | Financing
Summary of CLO
Spread	2.11%
STWD 2021-SIF1
Summary of CLO
Amount issued						$ 500,000
Percent of outstanding loan	3.00%
Debt, weighted average interest rate	5.88%
STWD 2021-SIF1 | Collateral assets
Summary of CLO
Count | Item	32	31
Amount issued	$ 483,243	$ 491,299
Carrying value	$ 506,443	$ 506,666
STWD 2021-SIF1 | Financing
Summary of CLO
Count | Item	1	1
Amount issued	$ 410,000	$ 410,000
Carrying value	$ 405,677	$ 405,319
STWD 2021-SIF1 | LIBOR | Collateral assets
Summary of CLO
Spread	3.91%	3.91%
STWD 2021-SIF1 | LIBOR | Financing
Summary of CLO
Spread	2.16%	2.15%