Land and Subsurface Interests - Additional Information (Detail)				3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 22, 2015	Jun. 17, 2015 USD ($) a	Jun. 01, 2015 USD ($) a $ / a	Sep. 30, 2015 USD ($) ft² a Job	Sep. 30, 2014 USD ($) a	Sep. 30, 2015 USD ($) ft² a Job	Sep. 30, 2014 USD ($) a $ / a	Dec. 31, 2011
Real Estate Properties [Line Items]
Area of a real estate property | ft²				1,270,000		1,270,000
Oil exploration lease period	8 years							8 years
Lease period where payment recognized	12 months							12 months
Amended oil exploration lease term						The terms of the lease state the Company will receive royalty payments if production occurs, and may receive additional annual rental payments if the lease is continued in years six through eight.
Lease income recognized from oil exploration lease				$ 456,000	$ 799,000	$ 1,400,000	$ 2,400,000
Area on which royalties received | a						800
Oil royalty income recognized				11,000	38,000	$ 60,000	167,000
Cash payments for release of surface entry rights						2,000	4,000
Fill Dirt Excavation [Member]
Real Estate Properties [Line Items]
Revenue generated from fill-dirt excavation agreement				$ 0	$ 16,000	73,000	139,000
Property East of Interstate 95 [Member]
Real Estate Properties [Line Items]
Revenue from land sold						$ 7,800,000	$ 7,800,000
Revenue per acre | $ / a							103,000
Gain (Loss) from sale of land							$ 3,900,000
Additional Gain (Loss) from sale of land							324,000
Halifax Humane Society, Inc. (HHS") [Member]
Real Estate Properties [Line Items]
Revenue from land sold							$ 391,500
Revenue per acre | $ / a							128,000
South of LPGA Boulevard East of Clyde Morris Boulevard [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a			3.0
Revenue from land sold			$ 505,000
Revenue per acre | $ / a			167,000
Gain (Loss) from sale of land			$ 476,000
Highlands County [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a		0.9
Revenue from land sold		$ 250,000
Gain (Loss) from sale of land		$ 223,000
Daytona Beach, Florida [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a				6		6
Volusia County, Florida [Member]
Real Estate Properties [Line Items]
Revenue recognized upon milestone achieved				$ 1,000,000
Volusia County, Florida [Member] | Minimum [Member]
Real Estate Properties [Line Items]
Potential jobs creation | Job				150		150
Land [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a				3.9		3.9
Land [Member] | Property East of Interstate 95 [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a				75.6	75.6	75.6	75.6
Land [Member] | Halifax Humane Society, Inc. (HHS") [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a					3.1		3.1
Gain (Loss) from sale of land							$ 347,000