Revenues (Narrative) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessor Lease Description [Line Items]
Total revenues	$ 9,240,000	$ 7,984,000	$ 8,503,000	$ 8,278,000	$ 8,913,000	$ 8,495,000	$ 10,844,000	$ 10,935,000	$ 34,005,000	$ 39,187,000	$ 45,890,000
Unpaid billed charges of rent and tenant reimbursements									$ 600,000	$ 200,000
Other Income [Member] | Contract Termination [Member]
Lessor Lease Description [Line Items]
Total revenues											$ 7,100,000