Identified Intangible Liabilities, Net Identified Intangible Liabilities, Net - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Identified intangible liabilities, net	$ 1,362,000		$ 1,362,000		$ 1,601,000
Amortization of identified intangible liabilities	78,000	$ 212,000	$ 239,000	$ 421,000
Finite lived intangible liabilities useful life			11 years 7 months 6 days		11 years 3 months 18 days
Below-market leases
Identified intangible liabilities, net	1,362,000		$ 1,362,000		$ 1,601,000
Finite lived intangible liabilities accumulated amortization	$ 586,000		$ 586,000		$ 702,000