Loans - Secured Loans in Non-Accrual Status (Details)		1 Months Ended	12 Months Ended
		Jun. 30, 2020 MortgageLoan	Dec. 31, 2021 USD ($) MortgageLoan	Dec. 31, 2020 USD ($) MortgageLoan	Dec. 31, 2019 USD ($)
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Number of secured loans | MortgageLoan		2	31	33
Secured loans, principal			$ 55,099,000	$ 74,080,000	$ 86,203,000
Accrued interest			459,000	716,000
Foregone interest			140,000
Non-accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Secured loans, principal			1,173,000	15,531,000
Accrued interest	[1]		13,000	368,000
Foregone interest			$ 1,000	$ 582,000
Principal [Member] | Non-accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Number of secured loans | MortgageLoan			4	3
Secured loans, principal	[2]		$ 1,044,000	$ 15,139,000
Advances [Member] | Non-accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Secured loans, principal			$ 116,000	$ 24,000

[1] Accrued interest in the table above is the amount of interest accrued prior to the loan being placed on non-accrual status, net of any payments received while in non-accrual status.

[2] In February 2022, three loans, with aggregate principal of approximately $987,000, included in the table above for 2021 paid in full or were brought current.