Related party transactions - Restricted stock grants (Details)				9 Months Ended	10 Months Ended	42 Months Ended	54 Months Ended
	Dec. 06, 2023 director shares	Apr. 07, 2021 shares	Apr. 15, 2020 shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2024 director shares	Sep. 30, 2024 shares	Sep. 30, 2024 shares
Related Party Transaction [Line Items]
Number of dividend equivalent units granted (in shares)					1,698
WMC
Related Party Transaction [Line Items]
Number of directors added to the company's board of directors | director	2				2
Director | Restricted Stock | WMC
Related Party Transaction [Line Items]
Shares of restricted common stock under equity incentive plans (in shares)	25,962
Manager Equity Incentive Plan | Related Party
Related Party Transaction [Line Items]
Shares of common stock company can award (in shares)			666,666
Shares available to be awarded under equity incentive plans (in shares)				406,539	406,539	406,539	406,539
Manager Equity Incentive Plan | Related Party | Maximum
Related Party Transaction [Line Items]
Value of shares granted in fiscal year | $				$ 300,000
2020 Equity Incentive Plan | Director | Restricted Stock
Related Party Transaction [Line Items]
Shares of restricted common stock under equity incentive plans (in shares)							232,467
2021 Equity Incentive Plan | Related Party
Related Party Transaction [Line Items]
Shares of common stock company can award (in shares)		573,425
Shares of restricted common stock under equity incentive plans (in shares)						0