ACCOUNTING POLICIES (Details 4)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)	May. 05, 2015 USD ($)	Dec. 31, 2014 USD ($)
Product Information [Line Items]
Document Period End Date			Sep. 30, 2015
Stock repurchase program, authorized amount					$ 25,000,000
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%	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	$ 11,200,000		$ 11,200,000			$ 15,500,000
Credit card chargeback allowance
Credit card chargeback allowance	182,000		182,000			129,000
Cost of goods sold
Total revenue, net	$ 391,211,000	$ 352,991,000	$ 1,177,568,000	$ 1,026,743,000
Total revenue, net (as a percent)	100.00%	100.00%	100.00%	100.00%
Cost of goods sold
Product costs and other cost of goods sold	$ 301,164,000	$ 270,219,000	$ 903,720,000	$ 786,981,000
Fulfillment and related costs	17,596,000	15,714,000	52,303,000	46,083,000
Total cost of goods sold	$ 318,760,000	$ 285,933,000	$ 956,023,000	$ 833,064,000
Product costs and other cost of goods sold (as a percent)	77.00%	77.00%	77.00%	77.00%
Fulfillment and related costs (as a percent)	4.00%	4.00%	4.00%	4.00%
Total cost of goods sold (as a percent)	81.00%	81.00%	81.00%	81.00%
Gross profit	$ 72,451,000	$ 67,058,000	$ 221,545,000	$ 193,679,000
Gross profit (as a percent)	19.00%	19.00%	19.00%	19.00%
Advertising expense
Advertising expense	$ 27,700,000	$ 23,100,000	$ 79,500,000	$ 64,800,000
Prepaid advertising expense	$ 1,900,000		$ 1,900,000			$ 2,000,000
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