Schedule II Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	$ 6,969,000		$ 6,124,000	$ 6,709,000
Charged to costs and expenses	13,071,000		15,443,000	13,295,000
Other	0		0	453,000
Deductions	13,671,000		14,598,000	14,333,000
Balance at end of year	6,369,000		6,969,000	6,124,000
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	5,528,000		4,944,000	5,386,000
Charged to costs and expenses	(497,000)		641,000	(728,000)
Other	0	[1]	0	414,000	[1]
Deductions	137,000		57,000	128,000
Balance at end of year	4,894,000		5,528,000	4,944,000
Allowance for Discounts [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	1,441,000		1,180,000	1,323,000
Charged to costs and expenses	13,568,000		14,802,000	14,023,000
Other	0		0	39,000	[1]
Deductions	13,534,000		14,541,000	14,205,000
Balance at end of year	1,475,000		1,441,000	1,180,000
Allowance for Sales Returns [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	31,464,000		29,033,000	25,074,000
Charged to costs and expenses	126,608,000		114,958,000	112,519,000
Other	0		0	4,128,000	[1]
Deductions	127,451,000		112,527,000	112,688,000
Balance at end of year	$ 30,621,000		$ 31,464,000	$ 29,033,000

[1] Allowances acquired through acquisition.