Stockholders' Equity and Non-Controlling Interests - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended		12 Months Ended
	Nov. 06, 2021 USD ($)	Nov. 05, 2021 USD ($)	Apr. 30, 2022 USD ($) shares	Mar. 31, 2024 USD ($) extension $ / shares shares	Mar. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2023 USD ($)	Dec. 31, 2018 shares	May 31, 2022 USD ($)
Equity Incentive Plans
Net income				$ 1,565	$ 2,287
Net income (loss) attributable to non-controlling interests				$ 5,528	7,787
CMBS JV
Equity Incentive Plans
Participation / Ownership %				51.00%
Class A Units
Equity Incentive Plans
Number of units outstanding (in shares) | shares				9,700,000
Woodstar II Portfolio | Class A Units
Equity Incentive Plans
Net income (loss) attributable to non-controlling interests				$ 4,700	4,700
Subsidiaries | Woodstar II Portfolio
Equity Incentive Plans
Conversion of stock ratio				1
Subsidiaries | Woodstar II Portfolio | Class A Units
Equity Incentive Plans
Shares issued (in shares) | shares							10,200,000
Right to receive additional shares (in shares) | shares				1,900,000			1,900,000
Subsidiaries | Woodstar II Portfolio | Class A Units | Non- Controlling Interests
Equity Incentive Plans
Redemption of units				$ 207,100		$ 207,100
Woodstar Fund
Equity Incentive Plans
Percentage of interest sold		20.60%
Contributions from non-controlling interests	$ 214,200	$ 216,000
Initial term				8 years
Number of extension options | extension				2
Extension term				1 year
CMBS JV
Equity Incentive Plans
Non-controlling interest				$ 124,900		$ 129,200
CMBS JV | Joint Venture Partner
Equity Incentive Plans
Ownership percentage				49.00%
CMBS JV | Woodstar II Portfolio | Class A Units
Equity Incentive Plans
Net income (loss) attributable to non-controlling interests				$ (1,000)	$ 700
Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan
Equity Incentive Plans
Number of shares of authorized for issuance (in shares) | shares			18,700,000
Common stock available for future grants (in shares) | shares				13,400,000
Employee Stock
Equity Incentive Plans
Purchase price of fair market value (as a percent)			85.00%
Maximum purchase value during calendar year, per employee			$ 25
Number of shares of authorized for issuance (in shares) | shares			2,000,000
Number of shares issued for future grants (in shares) | shares				66,315	65,026
Purchase price (in dollars per share) | $ / shares				$ 17.09	$ 14.91
Share-based expense				$ 300	$ 200
Common stock available for future issuance (in shares) | shares				1,700,000
ATM Agreement
Equity Incentive Plans
Authorized value of stock under ATM agreement								$ 500,000
Number of shares issued (in shares) | shares				0	0