ACCOUNTING POLICIES (Details 4) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Revenue recognition
Number of principal segments | segment									2
Product delivery period from date of shipment, minimum									1 day
Product delivery period from date of shipment, maximum									8 days
Co-branded credit card program
Maximum revenue from co-branded credit card program as a percentage of total net revenues									1.00%	1.00%	1.00%
Deferred revenue
Likelihood of gift card redemption to be remote, period									36 months
Sales returns allowance
Sales return period for which full refund will be granted									30 days
Sales return period for which reduced refund will be granted									30 days
Sales return received at returns processing facility for which reduced refund will be granted, period									45 days
Allowance for sales returns	$ 17,900				$ 15,500				$ 17,900	$ 15,500
Credit card chargeback allowance
Credit card chargeback allowance	240				129				240	129
Cost of goods sold
Total net revenue	480,270	$ 391,211	$ 388,013	$ 398,344	470,360	$ 352,991	$ 332,545	$ 341,207	$ 1,657,838	$ 1,497,103	$ 1,304,217
Total revenue, net (as a percent)									100.00%	100.00%	100.00%
Cost of goods sold
Product costs and other cost of goods sold									$ 1,279,766	$ 1,152,489	$ 999,519
Fulfillment and related costs									73,418	65,555	57,038
Total cost of goods sold	397,161	318,760	314,356	322,907	384,980	285,933	269,920	277,211	$ 1,353,184	$ 1,218,044	$ 1,056,557
Product costs and other cost of goods sold (as a percent)									77.00%	77.00%	77.00%
Fulfillment and related costs (as a percent)									4.00%	4.00%	4.00%
Total cost of goods sold (as a percent)									82.00%	81.00%	81.00%
Gross profit	83,109	$ 72,451	$ 73,657	$ 75,437	85,380	$ 67,058	$ 62,625	$ 63,996	$ 304,654	$ 279,059	$ 247,660
Gross profit (as a percent)									18.00%	19.00%	19.00%
Advertising expense
Advertising expense									$ 115,000	$ 99,600	$ 82,100
Prepaid advertising	$ 1,244				$ 1,518				1,244	1,518
Gain (Loss) on Investment in Precious Metals									$ (1,183)	$ (1,269)	$ (1,457)
Club O Loyalty Program, Gold
Club O loyalty program
Expiration period of Club O reward dollars after expiration of the customer's membership									90 days
Club O Loyalty Program, Silver
Club O loyalty program
Expiration period of Club O reward dollars after expiration of the customer's membership									90 days