Related Party Transactions (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Related Party Transaction [Line Items]
Interest and other income	$ 225,000	$ 764,000	$ 782,000	$ 1,382,000
Royalty-free license agreement written notice of termination period minimum (in months)			6 months
Number of assets owned that are maintained by Public Storage | item	2		2
Property management contract written notice of termination period minimum (in days)			60 days
Management fee expenses	$ 24,000	25,000	$ 48,000	49,000
Costs allocated from related party	21,000	19,000	41,000	37,000
Reimbursement to related party	187,000	168,000	373,000	336,000
Reimbursement from related party	9,000	10,000	18,000	20,000
Due to related parties	19,000		19,000		$ 106,000
Property Management [Member]
Related Party Transaction [Line Items]
Interest and other income	63,000	72,000	133,000	150,000
Operating expenses allocated to operating party	$ 89,000	$ 91,000	$ 188,000	$ 193,000