Offering Costs and Formation Transaction Expenses - Schedule of Immaterial Corrections on Financial Statements (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Formation transaction expenses	$ 500,421	$ 208,471	$ 1,261,223	$ 330,604
Net loss	(5,657,801)	(2,473,804)	(10,948,048)	(4,390,776)	10,585,390
Net cash provided by operating activities			17,760,375	26,267,639
Net cash provided by financing activities			31,577,669	6,328,556
Net change in cash and cash equivalents			31,556,528	(15,808,504)
As Reported [Member]
Formation transaction expenses
Net loss				(4,060,172)
Net cash provided by operating activities				26,598,243
Net cash provided by financing activities				5,997,952
Net change in cash and cash equivalents				(15,808,504)
Adjustment [Member]
Formation transaction expenses				330,604
Net loss				(330,604)
Net cash provided by operating activities				(330,604)
Net cash provided by financing activities				330,604
Net change in cash and cash equivalents
As Adjusted [Member]
Formation transaction expenses				330,604
Net loss				(4,390,776)
Net cash provided by operating activities				26,267,639
Net cash provided by financing activities				6,328,556
Net change in cash and cash equivalents				$ (15,808,504)