Secured Borrowings - Collateralized Loan Obligations (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security	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	$ 3,672,783	$ 3,676,224
Collateral assets
Summary of CLO
Face Amount	4,404,156	4,401,641
Carrying Value	4,455,549	4,454,087
Financing
Summary of CLO
Face Amount	3,684,162	3,689,140
Carrying Value	$ 3,672,783	$ 3,676,224
STWD 2022-FL3
Summary of CLO
Face Amount			$ 1,000,000
STWD 2022-FL3 | Collateral assets
Summary of CLO
Count | security	51	51
Face Amount	$ 1,000,000	$ 1,000,000
Carrying Value	$ 1,010,710	$ 1,010,051
STWD 2022-FL3 | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 842,500	$ 842,500
Carrying Value	$ 841,721	$ 842,374
STWD 2022-FL3 | Index | Collateral assets
Summary of CLO
Weighted Average Spread	3.48%	3.52%
STWD 2022-FL3 | SOFR | Financing
Summary of CLO
Weighted Average Spread	1.93%	1.93%
STWD 2021-HTS | Collateral assets
Summary of CLO
Count | security	1	1
Face Amount	$ 230,000	$ 230,000
Carrying Value	$ 231,239	$ 231,186
STWD 2021-HTS | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 210,091	$ 210,091
Carrying Value	$ 209,187	$ 208,961
STWD 2021-HTS | LIBOR | Collateral assets
Summary of CLO
Weighted Average Spread	3.87%	3.85%
STWD 2021-HTS | LIBOR | Financing
Summary of CLO
Weighted Average Spread	2.71%	2.71%
STWD 2021-FL2
Summary of CLO
Face Amount					$ 1,300,000
Percent of outstanding loan	7.00%
Debt, weighted average interest rate	7.44%
STWD 2021-FL2 | Collateral assets
Summary of CLO
Count | security	38	36
Face Amount	$ 1,278,175	$ 1,277,474
Carrying Value	$ 1,286,362	$ 1,284,240
STWD 2021-FL2 | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 1,077,375	$ 1,077,375
Carrying Value	$ 1,073,081	$ 1,072,403
STWD 2021-FL2 | Index | Collateral assets
Summary of CLO
Weighted Average Spread	3.90%	4.04%
STWD 2021-FL2 | LIBOR | Financing
Summary of CLO
Weighted Average Spread	1.80%	1.80%
STWD 2019-FL1
Summary of CLO
Face Amount							$ 1,100,000
STWD 2019-FL1 | Collateral assets
Summary of CLO
Count | security	16	16
Face Amount	$ 897,821	$ 902,799
Carrying Value	$ 902,795	$ 906,409
STWD 2019-FL1 | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 734,196	$ 739,174
Carrying Value	$ 734,196	$ 738,473
STWD 2019-FL1 | Index | Collateral assets
Summary of CLO
Weighted Average Spread	3.42%	3.67%
STWD 2019-FL1 | SOFR | Financing
Summary of CLO
Weighted Average Spread	1.64%	1.64%
STWD 2021-SIF2
Summary of CLO
Face Amount				$ 500,000
STWD 2021-SIF2 | Collateral assets
Summary of CLO
Count | security	31	31
Face Amount	$ 499,317	$ 495,587
Carrying Value	$ 511,809	$ 510,730
STWD 2021-SIF2 | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 410,000	$ 410,000
Carrying Value	$ 407,487	$ 407,260
STWD 2021-SIF2 | Index | Collateral assets
Summary of CLO
Weighted Average Spread	3.81%	3.73%
STWD 2021-SIF2 | SOFR | Financing
Summary of CLO
Weighted Average Spread	2.11%	2.11%
STWD 2021-SIF1
Summary of CLO
Face Amount						$ 500,000
Percent of outstanding loan	2.00%
Debt, weighted average interest rate	5.69%
STWD 2021-SIF1 | Collateral assets
Summary of CLO
Count | security	31	31
Face Amount	$ 498,843	$ 495,781
Carrying Value	$ 512,634	$ 511,471
STWD 2021-SIF1 | Financing
Summary of CLO
Count | security	1	1
Face Amount	$ 410,000	$ 410,000
Carrying Value	$ 407,111	$ 406,753
STWD 2021-SIF1 | Index | Collateral assets
Summary of CLO
Weighted Average Spread	3.98%	3.76%
STWD 2021-SIF1 | LIBOR | Financing
Summary of CLO
Weighted Average Spread	2.15%	2.15%