Summary of Recourse and Market-to-Market Provisions (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Goldman Sachs | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Aug. 19, 2022	Aug. 19, 2021
Extended maturity date	Aug. 19, 2024	Aug. 19, 2022
Wells Fargo | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Apr. 18, 2022	Apr. 18, 2022
Extended maturity date	Apr. 18, 2024	Apr. 18, 2022
Barclays | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Aug. 13, 2022	Aug. 13, 2022
Extended maturity date	Aug. 13, 2023	Aug. 13, 2022
Morgan Stanley | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	May 04, 2022	May 04, 2021
Extended maturity date	May 04, 2023	May 04, 2022
Institutional Financing | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Oct. 30, 2023	Oct. 30, 2023
Extended maturity date	Oct. 30, 2025	Oct. 30, 2025
US Bank | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Jul. 09, 2022	Jul. 09, 2022
Extended maturity date	Jul. 09, 2024	Jul. 09, 2024
Bank of America | Senior Secured and Secured Credit Agreements | Repurchase Agreements | Loans Investment
Debt Instrument [Line Items]
Recourse guarantee percentage	25.00%	25.00%
Initial maturity date	Sep. 29, 2022	Sep. 29, 2021
Extended maturity date	Sep. 29, 2022	Sep. 29, 2022
Institutional Lender | Asset-specific Financing
Debt Instrument [Line Items]
Initial maturity date	Dec. 15, 2021	Dec. 15, 2021
Extended maturity date	Dec. 15, 2022	Dec. 15, 2022