Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 54,782	$ 39,627	$ 46,312
Charged to Costs and Expenses	50,116	76,507	60,342
Deductions	(58,038)	(61,352)	(67,027)
Balance at End of Period	46,860	54,782	39,627
Uncollectible accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	3,069	2,778	2,543
Charged to Costs and Expenses	(351)	461	1,086
Deductions	(182)	(170)	(851)
Balance at End of Period	2,536	3,069	2,778
Reserve for potential product obsolescence
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	8,273	8,471	9,872
Charged to Costs and Expenses	7,902	8,099	6,844
Deductions	(6,224)	(8,297)	(8,245)
Balance at End of Period	9,951	8,273	8,471
Reserve for sales returns and allowances
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	43,440	28,378	33,897
Charged to Costs and Expenses	42,565	67,947	52,412
Deductions	(51,632)	(52,885)	(57,931)
Balance at End of Period	$ 34,373	$ 43,440	$ 28,378