Loans - Secured Loans Characteristics (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2020 MortgageLoan	Dec. 31, 2020 USD ($) Loan County MortgageLoan	Dec. 31, 2019 USD ($) Loan County MortgageLoan	Dec. 31, 2018 USD ($)
Secured Loan Transactions [Line Items]
Number of secured loans | Loan		33	47
Secured loans - principal (in Dollars)		$ 74,080	$ 86,203	$ 97,438
Average secured loan - principal (in Dollars)		$ 2,245	$ 1,834
Average principal as percent of total principal		3.00%	2.10%
Average principal as percent of partners’ capital, net of formation loan		2.90%	2.00%
Average principal as percent of total assets		2.70%	1.90%
Largest secured loan - principal (in Dollars)		$ 10,200	$ 10,200
Largest principal as percent of total principal		13.80%	11.80%
Largest principal as percent of partners’ capital, net of formation loan		13.00%	10.90%
Largest principal as percent of total assets		12.10%	10.80%
Smallest secured loan - principal (in Dollars)		$ 46	$ 51
Smallest principal as percent of total principal		0.10%	0.10%
Smallest principal as percent of partners’ capital, net of formation loan		0.10%	0.10%
Smallest principal as percent of total assets		0.10%	0.10%
Number of California counties where security is located | County		14	15
Largest percentage of principal in one California county		40.00%	38.20%
Number of secured loans with filed notice of default | MortgageLoan	2	33	47
Secured loans in foreclosure - principal (in Dollars)			$ 2,939
Prepaid interest			$ 121
Minimum [Member]
Secured Loan Transactions [Line Items]
Secured loans - interest rate (fixed)		5.00%	5.00%
Maximum [Member]
Secured Loan Transactions [Line Items]
Secured loans - interest rate (fixed)		10.80%	10.80%
Filed Notice of Default [Member]
Secured Loan Transactions [Line Items]
Number of secured loans with filed notice of default | MortgageLoan			1
Prepaid Interest [Member]
Secured Loan Transactions [Line Items]
Number of secured loans with filed notice of default | MortgageLoan			2