Summary of Significant Accounting Policies - Effect of Correction on Combined Financial Statements (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Deferred costs, net	$ 3,310,685	$ 1,684,758
Formation transaction expenses	263,822	362,591
Net income	3,736,707	2,283,399
Net cash provided by operating activities	4,153,101	6,560,057
Net cash used in financing activities	(8,090,469)	(4,611,157)
Net change in cash and cash equivalents	(8,370,650)	(1,088,957)
As reported [Member]
Deferred costs, net		2,140,059
Members' deficiency		(12,841,459)
Formation transaction expenses
Net income		2,645,990
Net cash provided by operating activities		6,922,648
Net cash used in financing activities		(4,973,748)
Net change in cash and cash equivalents		(1,088,957)
Adjustments [Member]
Deferred costs, net		(455,301)
Members' deficiency		(455,301)
Formation transaction expenses		362,591
Net income		(362,591)
Net cash provided by operating activities		(362,591)
Net cash used in financing activities		362,591
Net change in cash and cash equivalents
As adjusted [Member]
Deferred costs, net		1,684,758
Members' deficiency		(13,296,760)
Formation transaction expenses		362,591
Net income		2,283,399
Net cash provided by operating activities		6,560,057
Net cash used in financing activities		(4,611,157)
Net change in cash and cash equivalents		$ (1,088,957)