Subsequent Events -Additional Information (Detail)										3 Months Ended
	Apr. 22, 2016 USD ($) ft² a $ / shares	Apr. 15, 2016 USD ($)	Apr. 13, 2016 USD ($) a $ / shares	Apr. 06, 2016 USD ($) $ / shares	Apr. 05, 2016 USD ($) ft² $ / shares	Mar. 30, 2016 USD ($)	Mar. 28, 2016 USD ($)	Feb. 18, 2016 USD ($) a	Feb. 12, 2016 USD ($)	Mar. 31, 2016 USD ($) ft² a	Mar. 31, 2015 USD ($)	Dec. 31, 2015 a
Subsequent Event [Line Items]
Area of lease | a										10,500
Weighted average remaining lease term								8 years 2 months 12 days
Gain (loss) on sale of property							$ 11,400,000			$ 134,000	$ 277,000
Area of a real estate property								0.37		1,700,000		160
Revenue from land sold						$ 2,000,000				$ 2,200,000
Acquisition price of real state property								$ 2,500,000
Wells Fargo Mortgage Note Payable [Member]
Subsequent Event [Line Items]
Mortgage loan agreement, description										The Mortgage Loan has a 5-year term with two years interest only and interest and a 25-year amortization for the balance of the term.
Daytona Beach, Florida [Member]
Subsequent Event [Line Items]
Area of a real estate property | a										6		6
Revenue from land sold									$ 190,000
Sebring, Florida [Member]
Subsequent Event [Line Items]
Gain (loss) on sale of property										$ 210,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Tenant improvements					$ 4,000,000
Area of a real estate property | a	21		600
Revenue from land sold			$ 9,000,000
Acquisition price of real state property			3,600,000
Repurchase of common stock, authorized amount			$ 10,000,000
Subsequent Event [Member] | Wells Fargo Mortgage Note Payable [Member]
Subsequent Event [Line Items]
Proceeds from first mortgage bond		$ 25,000,000
Term of mortgage loan		5 years
Interest rate on mortgage loan		3.17%
Long-term debt LIBOR plus interest rate, reckoning period		30 days
Line of credit facility, basis points added to LIBOR interest rate		1.90%
Subsequent Event [Member] | Land Venture Partners, LLC [Member]
Subsequent Event [Line Items]
Sale of subsurface interest area of land | a			500,000
Sale price of subsurface interest area of land			$ 24,000,000
Gain (loss) on sale of subsurface interest area of land after tax			$ 22,600,000
Gain (loss) on sale of subsurface interest area of land per share after tax | $ / shares			$ 2.40
Subsequent Event [Member] | Winter Park, Florida [Member]
Subsequent Event [Line Items]
Area of lease | ft²					40,000
Area of land in percentage					36.00%
Lease term					15 years
Area of land multi-tenant retail center | ft²					112,000
Subsequent Event [Member] | Daytona Beach, Florida [Member]
Subsequent Event [Line Items]
Weighted average remaining lease term	9 years 3 months 18 days				3 years 9 months 18 days
Proceeds from building	$ 3,000,000				$ 5,200,000
Gain (loss) on sale of property	$ 822,000				$ 197,000
Loss on sale of building per share after tax | $ / shares	$ 0.09				$ 0.02
Area of building sold | ft²	15,360
Subsequent Event [Member] | Sebring, Florida [Member]
Subsequent Event [Line Items]
Weighted average remaining lease term				3 years 1 month 6 days
Proceeds from building				$ 2,400,000
Gain (loss) on sale of property				$ 210,000
Loss on sale of building per share after tax | $ / shares				$ 0.02