Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 46,860	$ 54,782	$ 39,627
Charged to Costs and Expenses	54,525	50,116	76,507
Deductions	(57,596)	(58,038)	(61,352)
Balance at End of Period	43,789	46,860	54,782
Uncollectible accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	2,536	3,069	2,778
Charged to Costs and Expenses	541	(351)	461
Deductions	(149)	(182)	(170)
Balance at End of Period	2,928	2,536	3,069
Reserve for potential product obsolescence
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	9,951	8,273	8,471
Charged to Costs and Expenses	16,257	7,902	8,099
Deductions	(16,721)	(6,224)	(8,297)
Balance at End of Period	9,487	9,951	8,273
Reserve for sales returns and allowances
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	34,373	43,440	28,378
Charged to Costs and Expenses	37,727	42,565	67,947
Deductions	(40,726)	(51,632)	(52,885)
Balance at End of Period	$ 31,374	$ 34,373	$ 43,440