Offering Costs and Formation Transaction Expenses - Additional Information (Detail) (USD $)	6 Months Ended	9 Months Ended
	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012 Adjustment [Member]	Sep. 30, 2012 Supervisor [Member]	Dec. 31, 2011 Supervisor [Member]
Related Party Transaction [Line Items]
Formation Transaction Expense Included in Deferred Offering Costs	$ 538,123
External offering costs		3,020,383		82,822
Deferred costs		1,335,625	702,424
Deferred costs due to supervisors					435,194	922,728
Additional offering costs		$ 172,991	$ 96,750