Organization and Capitalization - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 Segment shares	Dec. 31, 2014 shares	Dec. 06, 2013 $ / shares shares	Dec. 31, 2012 shares	Dec. 31, 2011 shares	Dec. 31, 2009 shares	Dec. 31, 2007 shares	Dec. 27, 2007 shares	Jul. 12, 2006 shares
Organization and Capitalization [Line Items]
Common stock, shares authorized	750,000,000	750,000,000		130,322,900	126,863,000	38,635,550	14,416,250		11,533,000
Preferred stock, shares authorized			25,000,000	65,693,245	62,693,245	21,734,402		6,500,000
Preferred stock, par value (in dollars per share) | $ / shares			$ 0.01
Number of business segments | Segment	1
Minimum [Member]
Organization and Capitalization [Line Items]
Common stock, shares authorized			225,000,000
Maximum [Member]
Organization and Capitalization [Line Items]
Common stock, shares authorized			750,000,000