Summary of Significant Accounting Policies - Reconciliation of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 13,244
Provision for credit losses	$ 2,924	$ 1,107	$ 2,257