Offering Costs and Formation Transaction Expenses - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Registrant incurred capitalized external offering costs	$ 1,826,684
External offering costs during period	74,340	122,605
Offering costs Due to Supervisor	48,636		422,031
Additional offering costs for work done by Supervisor's employees	43,372	23,024
Accumulated correction impacted amount	$ 1,826,684	$ 227,846	$ 1,752,344