Description of Leasing Arrangements - Additional Information (Detail)			3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 29, 2020 USD ($)	Jul. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) Billboard_Face LandLease Parcel	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Billboard_Face LandLease Parcel Location	Sep. 30, 2019 USD ($)	May 31, 2020 USD ($)	May 31, 2019 USD ($)
Operating Leased Assets [Line Items]
Number of long-term land leases | LandLease			9		9
Number of parcels upon which improvements have been completed | Parcel			8		8
Estimated real property taxes attributable to the company land			$ 315,000	$ 341,000	$ 997,000	$ 1,023,000
Number of long-term land leases with contingent rent receivable | LandLease			2		2
Contingent revenue from leasing of parcel of land			$ 18,000	24,000	$ 76,000	87,000
Parcel (6C) [Member]
Operating Leased Assets [Line Items]
Notice period of lease					30 days
Annual rent	$ 220,000
Real estate taxes paid by the lessee	$ 311,000
Triple Net Lease [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Term of leases			99 years		99 years
Lamar Lease [Member]
Operating Leased Assets [Line Items]
Number of advertising locations | Location					23
Number of billboard faces along interstate and primary highways leased | Billboard_Face			44		44
Lease expiration year					2045
Annual increment in base rent of lease, percentage					2.75%
Period for advance receipt of percentage of gross revenue on leases					12 months
Period to recognize specified lease revenue					30 days
Percentage of revenue due in proportion of gross revenues from each standard billboard					30.00%
Percentage of revenue due in proportion of gross revenues from each electronic billboard					20.00%
Percentage rent							$ 139,000	$ 133,000
Lamar Lease [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Percentage of commissions paid to unrelated third parties adjusted in gross revenues from standard billboard					15.00%
Percentage of commissions paid to unrelated third parties adjusted in gross revenues from electronic billboard					15.00%
Metropark Ltd [Member]
Operating Leased Assets [Line Items]
Term of leases			10 years		10 years
Contingent revenue from leasing of parcel of land			$ 0	$ 24,000		$ 95,000
Notice period of lease					30 days
Decrease in revenue					$ 34,000
Threshold parking revenue per month for scheduled rental payments by lessee		$ 70,000
Percentage of revenue in excess of threshold parking revenue		50.00%
Lease income from rent			11,000
Payments receivable			$ 227,000		$ 227,000
Percentage of operations return to pre-pandemic levels			80.00%		80.00%