Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Parenthetical) (Detail) - Class A Common Stock [Member] - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Class of Stock [Line Items]
Deferred stock units held by directors	281,143	244,536	281,143	244,536
Common stock, shares issued under dividend reinvestment program	646	272	971	553