Schedule II - Valuation And Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 28,562	$ 19,288	$ 19,981
Charged to Costs and Expenses	56,345	54,457	50,885
Deductions	(53,355)	(45,183)	(51,578)
Balance at End of Period	31,552	28,562	19,288
Uncollectible accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	10,940	2,864	2,714
Charged to Costs and Expenses	9,586	11,803	303
Deductions	(18,377)	(3,727)	(153)
Balance at End of Period	2,149	10,940	2,864
Reserve for sales returns and allowances
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	17,622	16,424	17,267
Charged to Costs and Expenses	46,759	42,654	50,582
Deductions	(34,978)	(41,456)	(51,425)
Balance at End of Period	$ 29,403	$ 17,622	$ 16,424