Equity - Summary of Class A Common Stock Issuances (Parenthetical) (Detail) - shares	1 Months Ended				12 Months Ended
	Jun. 30, 2015	May 31, 2015	Apr. 30, 2015	May 31, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Shares issued				25,875,000	1,070	34,780,622	28,275,006
Class A Common Stock [Member]
Class of Stock [Line Items]
Shares issued	11,500,000	280,025	23,000,000		0	34,780,025