Fair Value Measurements for Assets Measured at Fair Value on Nonrecurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Assets		$ 0
Fair Value Measured on Nonrecurring Basis Gains (Losses), Total	(17,906,659)
El Paso
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
El Paso Real Estate Transaction	3,024,550
Fair Value Measured on Nonrecurring Basis Gains (Losses), Total	3,958,122
Foundation
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Assets	7,475,459
Liabilities	(15,401,366)
Fair Value Measured on Nonrecurring Basis Gains (Losses), Total	(21,864,781)
Significant Other Observable Inputs (Level 2) | El Paso
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
El Paso Real Estate Transaction	2,573,633
Significant Unobservable Inputs (Level 3) | El Paso
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
El Paso Real Estate Transaction	450,917
Significant Unobservable Inputs (Level 3) | Foundation
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Assets	7,475,459
Liabilities	$ (15,401,366)