RETURNS RESERVE (Schedule of Returns Reserve Included as Other Accrued Expenses and Current Liabilities in Accompanying Consolidated Balance Sheets) (Details) - Allowance for Sales Returns [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 740	$ 870	$ 762
Provision for estimated returns	19,011	14,929	13,225
Actual returns	(18,883)	(15,059)	(13,117)
Balance at end of year	$ 868	$ 740	$ 870