Loans - Secured Loans in Non-Accrual Status (Details)		1 Months Ended	12 Months Ended
		Mar. 31, 2022 USD ($) MortgageLoan	Dec. 31, 2021 USD ($) MortgageLoan	Dec. 31, 2020 USD ($) MortgageLoan	Dec. 31, 2019 USD ($)
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Number of secured loans | MortgageLoan		1	54	82
Principal		$ 586,000	$ 81,097,000	$ 82,275,000	$ 70,660,000
Accrued interest			$ 529,000	684,000
Forgone interest				$ 42,000
Non-Accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Number of secured loans | MortgageLoan			2	3
Principal			$ 1,612,000	$ 3,531,000
Accrued interest			35,000	181,000
Forgone interest			67,000	63,000
Principal [Member] | Non-Accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Principal	[1]		1,576,000	3,340,000
Advances [Member] | Non-Accrual Status [Member]
Loans Details Secured Loans In Nonaccrual Status [Line Items]
Principal			$ 1,000	$ 10,000

[1] In March 2022, one loan, with principal of approximately $586,000 included in the 2021 table above was paid in full.