Summary of Quarterly Financial Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 22,503,218	$ 21,292,574	$ 19,931,208	$ 19,407,941	$ 18,455,140	$ 17,098,173	$ 15,705,274	$ 15,351,917	$ 83,134,941	$ 66,610,504	$ 49,396,078
Total operating expenses	19,315,207	17,229,995	16,667,044	16,557,885	17,351,457	17,000,260	16,136,742	15,455,345	69,770,131	65,943,804	58,611,867
Operating income (loss)	3,188,011	4,062,579	3,264,164	2,850,056	1,103,683	97,913	(431,468)	(103,428)	13,364,810	666,700	(9,215,789)
Net loss	(2,639,352)	(689,288)	(1,949,099)	(2,167,459)	(3,852,041)	(4,620,823)	(5,091,133)	(5,451,145)	(7,445,198)	(19,015,142)	(21,834,237)
Net loss attributable to the Company	$ (2,637,508)	$ (693,245)	$ (1,949,079)	$ (2,167,224)	$ (3,843,894)	$ (4,610,650)	$ (5,087,074)	$ (5,432,094)	$ (7,447,056)	$ (18,973,712)	$ (21,357,429)
Net loss per share-basic and diluted	$ (0.05)	$ (0.01)	$ (0.04)	$ (0.05)	$ (0.08)	$ (0.11)	$ (0.12)	$ (0.15)