Land and Development Costs and Subsurface Interests - Land Impairments (Details)	3 Months Ended			12 Months Ended
	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) a item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) a
Real Estate Properties [Line Items]
Impairment Charges	$ 1,970,822	$ 209,908	$ 510,041	$ 2,180,730	$ 510,041	$ 421,040
Land [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a				9,800		99.7
Impairment Charges					$ 0	$ 0
Undeveloped Land [Member]
Real Estate Properties [Line Items]
Impairment Charges				$ 1,000,000
Town Center Sales Agreements | Undeveloped Land [Member]
Real Estate Properties [Line Items]
Area of a real estate property | a				8
Number of executed purchase and sale agreements | item				2
Number of executed purchase and sale agreements impaired | item				10
Town Center Sales Agreement, Impaired Contract 1 [Member]
Real Estate Properties [Line Items]
Impairment Charges	717,000
Town Center Sales Agreement, Impaired Contract 2 [Member]
Real Estate Properties [Line Items]
Impairment Charges	$ 311,000