Schedule II-Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 1,255	$ 1,255	$ 1,256
Additions	35	189	277
Deductions	(35)	(189)	(278)
Balance at end of year	1,255	1,255	1,255
Allowance For Sales Returns And Product Warranty [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	62,376	66,221	63,690
Additions	105,987	97,546	104,810
Deductions	(95,754)	(101,391)	(102,279)
Balance at end of year	72,609	62,376	66,221
Allowance For Price Protection [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	1,806	4,273	1,783
Additions	7,467	7,534	8,352
Deductions	(7,148)	(10,001)	(5,862)
Balance at end of year	$ 2,125	$ 1,806	$ 4,273