Stock Transactions and Unit Redemptions - Schedule of Share Repurchase Activity (Detail) - Class A Common Stock - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended	15 Months Ended	20 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2020	Mar. 31, 2020
Class of Stock [Line Items]
Shares repurchased (in shares)	4,568,002	4,568,002	4,568,002	4,568,002
Treasury stock repurchases (in shares)	0
Average Price Paid per Unit or Share (in dollars per share)	$ 0	$ 9.32		$ 9.32
Total Number of Shares Repurchased as Part of Publicly Announced Program	0	4,568,002	4,568,002
Approximate Dollar Value of Units and Shares That May Yet Be Repurchased/ Purchased Under the Program	$ 157,413	$ 157,413	$ 157,413	$ 157,413