Summary of Total Reserves Included in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Receivables Net Current [Abstract]
Reduction to accounts receivable	$ 7,743	$ 8,352
Component of accrued expenses	59,942	42,618
Total reserves	$ 67,685	$ 50,970	$ 51,818	$ 51,503