QUARTERLY RESULTS OF OPERATIONS (unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue, net
Direct	$ 46,468	$ 34,215	$ 33,936	$ 40,897	$ 47,256	$ 34,749	$ 33,443	$ 48,161	$ 155,516	$ 163,609	$ 209,646
Fulfillment partner	295,566	221,137	205,600	221,470	266,821	204,989	201,549	217,309	943,773	890,668	880,227
Total net revenue	342,034	255,352	239,536	262,367	314,077	239,738	234,992	265,470	1,099,289	1,054,277	1,089,873
Cost of goods sold
Direct	41,114	30,684	31,108	37,630	43,927	32,472	30,231	43,030	140,536	149,660	187,124
Fulfillment partner	239,709	178,126	165,259	177,229	219,289	168,893	164,991	172,356	760,323	725,529	713,109
Total cost of goods sold	280,823	208,810	196,367	214,859	263,216	201,365	195,222	215,386	900,859	875,189	900,233
Gross profit	61,211	46,542	43,169	47,508	50,861	38,373	39,770	50,084	198,430	179,088	189,640
Operating expenses:
Sales and marketing	20,581	14,899	13,512	14,475	18,911	13,822	13,655	15,425	63,467	61,813	61,334
Technology	18,622	16,085	15,122	15,638	16,404	17,171	16,808	16,660	65,467	67,043	58,260
General and administrative	14,093	13,828	14,516	14,822	17,734	15,321	16,725	17,986	57,259	67,766	55,650
Restructuring	23	(45)		98					76		(569)
Total operating expenses	53,319	44,767	43,150	45,033	53,049	46,314	47,188	50,071	186,269	196,622	174,675
Operating income (loss)	7,892	1,775	19	2,475	(2,188)	(7,941)	(7,418)	13	12,161	(17,534)	14,965
Interest income	30	30	27	29	40	23	46	52	116	161	157
Interest expense	(154)	(194)	(253)	(208)	(517)	(662)	(630)	(676)	(809)	(2,485)	(2,962)
Other income (expense), net	1,322	1,213	719	432	(684)	553	220	189	3,686	278	2,088
Income (loss) before income taxes	9,090	2,824	512	2,728	(3,349)	(8,027)	(7,782)	(422)	15,154	(19,580)	14,248
Provision (benefit) for income taxes	303	131	42	9	60	(240)	16	22	485	(142)	359
Net income (loss)	8,787	2,693	470	2,719	(3,409)	(7,787)	(7,798)	(444)	14,669	(19,438)	13,889
Deemed dividend related to redeemable common stock							(2)	(10)		(12)	(112)
Net income (loss) attributable to common shares	$ 8,787	$ 2,693	$ 470	$ 2,719	$ (3,409)	$ (7,787)	$ (7,800)	$ (454)	$ 14,669	$ (19,450)	$ 13,777
Net income (loss) per common share-basic:
Net income per share-basic (in dollars per share)	$ 0.37	$ 0.11	$ 0.02	$ 0.12	$ (0.15)	$ (0.33)	$ (0.34)	$ (0.02)	$ (0.63)	$ 0.84	$ (0.60)
Weighted average common shares outstanding-basic (in shares)	23,450	23,447	23,437	23,392	23,278	23,276	23,265	23,215	23,387	23,259	23,019
Net income per common share-diluted:
Net income per share-diluted (in dollars per share)	$ 0.37	$ 0.11	$ 0.02	$ 0.12	$ (0.15)	$ (0.33)	$ (0.34)	$ (0.02)	$ (0.62)	$ 0.84	$ (0.59)
Weighted average common shares outstanding-diluted (in shares)	24,064	23,754	23,464	23,414	23,278	23,276	23,265	23,215	23,672	23,259	23,366