Overview - Schedule of Shares and Operating Group Units (Detail) - shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class A Shares
Class of Stock
Common stock and operating group units outstanding	21,284,945	19,905,126	18,957,321	18,484,326
Class B Shares
Class of Stock
Common stock and operating group units outstanding	29,208,952	29,458,948	33,933,948	29,731,702
Group A Units
Class of Stock
Common stock and operating group units outstanding	16,019,506
Group A-1 Units
Class of Stock
Common stock and operating group units outstanding	9,779,446
Group B Units
Class of Stock
Common stock and operating group units outstanding	21,284,945
Group E Units
Class of Stock
Common stock and operating group units outstanding	13,450,821
Group P Units
Class of Stock
Common stock and operating group units outstanding	3,410,000