Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	$ 4,967,000		$ 4,425,000	$ 4,246,000
Charged to costs and expenses	10,684,000		11,634,000	10,988,000
Other	0		0	0
Deductions	9,964,000		11,092,000	10,809,000
Balance at end of year	5,687,000		4,967,000	4,425,000
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	3,824,000		3,353,000	3,201,000
Charged to costs and expenses	325,000		970,000	949,000
Other	0		0	0
Deductions	(339,000)		499,000	797,000
Balance at end of year	4,488,000		3,824,000	3,353,000
Allowance for Discounts [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	1,143,000		1,072,000	1,045,000
Charged to costs and expenses	10,359,000		10,664,000	10,039,000
Other	0		0	0
Deductions	10,303,000		10,593,000	10,012,000
Balance at end of year	1,199,000		1,143,000	1,072,000
Allowance for Sales Returns [Member]
Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of year	35,916,000		40,176,000	38,812,000
Charged to costs and expenses	132,390,000		137,416,000	138,407,000
Other	6,670,000	[1]	0	0
Deductions	117,543,000		141,676,000	137,043,000
Balance at end of year	$ 57,433,000		$ 35,916,000	$ 40,176,000

[1] The other addition to the allowance for sales returns represents the cumulative effect of the changes made to our consolidated balance sheet as of January 1, 2018 for the adoption of ASU 2014-09, Revenue from Contracts with Customers. For information related to our adoption of ASU 2014-09 see Note 1 "Summary of Significant Accounting Policies" of the Notes to our Consolidated Financial Statements in Item 8 of this Report.