Description of Leasing Arrangements - Additional Information (Detail)			3 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 01, 2018 USD ($)	Mar. 31, 2019 USD ($) Billboard_Face LandLease Parcel Building Location	Mar. 31, 2018 USD ($) Tenant
Operating Leased Assets [Line Items]
Number of long-term land leases | LandLease			10
Number of parcels upon which improvements have been completed | Parcel			7
Estimated real property taxes attributable to the company land			$ 341,000	$ 308,000
Number of long-term land leases with contingent rent receivable | LandLease			2
Contingent revenue from leasing of parcel of land			$ 27,000	29,000
Parcel (6B) [Member]
Operating Leased Assets [Line Items]
Number of parcels upon which construction has commenced | Parcel			1
Number of residential units commenced construction | Building			169
Parcel 20 [Member]
Operating Leased Assets [Line Items]
Lessee option to extend			360 months
Impairment loss	$ 1,832,000
Parcel 20 [Member] | First 36 Months [Member]
Operating Leased Assets [Line Items]
Monthly rent receivable		$ 7,471
Parcel 20 [Member] | After 36 Months [Member]
Operating Leased Assets [Line Items]
Monthly rent receivable		$ 8,488
Lessee, payment terms and conditions			monthly payments thereafter of $8,488 plus an amount equal to 1/12th of the product of (a) 5.5% and the difference between (x) $2,750,000 and (y) the aggregate of the prior monthly payments of $8,488. The Restated Lease is a triple net lease.
Building and related improvements sold to tenant			$ 2,750,000
Lease principal payments interest percentage			5.50%
Parcel (6C) [Member]
Operating Leased Assets [Line Items]
Notice period of lease			30 days
Annual rent			$ 200,000
Real estate taxes paid by the lessee			$ 311,000
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
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%
Metropark Ltd [Member]
Operating Leased Assets [Line Items]
Contingent revenue from leasing of parcel of land			$ 47,000	21,000
Term of leases			10 years
Notice period of lease			30 days
Additional to contingent rent in excess of estimate			$ 23,000
Steeple Street Building [Member]
Operating Leased Assets [Line Items]
Annual rent				$ 95,000
Number of tenants occupying building | Tenant				4
Percentage of building occupied by tenants				49.00%
Term of short term leases			Five years or less
Tenant reimbursement revenue				$ 9,000