Stock Transactions and Unit Redemptions - Gross Unit Redemptions and Share Repurchases of Class A Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended						3 Months Ended						9 Months Ended
	Sep. 30, 2023	Aug. 31, 2023	Jul. 31, 2023	Sep. 30, 2022	Aug. 31, 2022	Jul. 31, 2022	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Class of Stock [Line Items]
Redemptions (in shares)							0	422,000	23,000	214,000	1,010,000	43,000	445,000	1,267,000
Repurchases (in shares)	3,474,000	1,612,000	3,000,000	3,448,000	5,916,000	3,033,000	8,087,000	9,814,000	846,000	12,397,000	8,745,000	0	18,747,000	21,142,000
Total redemptions and repurchases (in shares)													19,191,000	22,409,000
Redemptions, weighted average price paid per unit or share (in dollars per share)							$ 0	$ 4.91	$ 3.90	$ 3.91	$ 3.81	$ 4.01	$ 4.85	$ 3.83
Repurchases, weighted average price paid per unit or shares (in dollars per share)	$ 5.24	$ 5.01	$ 4.68	$ 4.11	$ 4.14	$ 3.70		$ 4.44	$ 4.97		$ 3.36	$ 0	4.70	3.75
Total redemptions and repurchases, weighted average price paid per unit or shares (in dollars per share)													$ 4.70	$ 3.76
Approximate Dollar Value of Units and Shares That Could Be Redeemed/ Purchased Under the Program at September 30, 2023	$ 359,656			$ 107,655			$ 359,656			$ 107,655			$ 359,656	$ 107,655
Weighted-average price for redemption of limited partnership units (in dollars per share)										$ 4.05				$ 3.88
Aggregate purchase price of Class A common stock													$ 86,537	$ 79,295
Class A Common Stock
Class of Stock [Line Items]
Repurchases (in shares)							8,086,750			12,396,735			18,746,467	21,142,045
Approximate Dollar Value of Units and Shares That Could Be Redeemed/ Purchased Under the Program at September 30, 2023	$ 359,700						$ 359,700						$ 359,700
Conversion, shares issued (in shares)							200,000			5,800,000			20,400,000	13,700,000
Stock issued during period, shares, exchange of units										6,100,000			13,500,000	10,600,000
Stock repurchased during period (in shares)							8,100,000			12,400,000			18,700,000	21,100,000
Aggregate purchase price of Class A common stock							$ 40,300			$ 49,900			$ 88,100	$ 79,300
Stock repurchased, weighted average price (in dollars per share)							$ 4.99			$ 4.03			$ 4.70	$ 3.75
Limited Partnership
Class of Stock [Line Items]
Redeemed limited partnership units (in shares)										200,000			300,000	1,200,000
Aggregate redemption price of limited partnership units										$ 800			$ 1,400	$ 4,500
Weighted-average price for redemption of founding/working partner units (in dollars per share)													$ 4.71
FPUs
Class of Stock [Line Items]
Redeemed limited partnership units (in shares)										27,000			200,000	100,000
Aggregate redemption price of limited partnership units										$ 100			$ 800	$ 300
Weighted-average price for redemption of founding/working partner units (in dollars per share)										$ 2.96			$ 5.11	$ 3.23