Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 4,786	$ 2,933	$ 2,971
Write-Offs	3,875	470	1,251
Additions	6,321	2,323	1,213
Ending Balance	7,232	4,786	2,933
Sales Returns and Allowances [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	676	741	480
Write-Offs	61,935	83,474	86,727
Additions	61,935	83,409	86,988
Ending Balance	$ 676	$ 676	$ 741