Impairment of Long-Lived Assets - Additional Information (Detail)			3 Months Ended								12 Months Ended
	Apr. 17, 2015 USD ($)	Dec. 20, 2013 USD ($) a $ / a	Dec. 31, 2015 USD ($) a	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($) Property	Dec. 31, 2014 USD ($) a	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) a	Dec. 31, 2014 USD ($) a	Dec. 31, 2013 USD ($) a	Dec. 31, 2015 ft²
Property Plant And Equipment [Line Items]
Impairment Charges		$ 616,000	$ 0	$ 0	$ 0	$ 510,041	$ 0	$ 421,040	$ 0	$ 0	$ 510,041	$ 421,040	$ 616,278
Number of income properties held for sales | Property						2
Gain (loss) on sale of property	$ (497,000)				$ 13,000	$ (277,000)		(228,000)					$ 1,216,000
Estimated closing costs						$ 233,000		$ 193,000
Impairment analysis for specified acres of land | a													6.23
Area of land used for transaction | a		3.21											3.21
Area of land sold			160								160			1,700,000
Revenue from land sold											$ 22,500,000	$ 8,800,000	$ 3,000,000
CarMax [Member]
Property Plant And Equipment [Line Items]
Revenue from land sold		$ 1,050,000
Revenue per acre | $ / a		168,500
Land [Member]
Property Plant And Equipment [Line Items]
Area of land sold | a			114.03				99.66				114.03	99.66	11.655
Land [Member] | CarMax [Member]
Property Plant And Equipment [Line Items]
Area of land sold | a		6.23