CONDENSED CONSOLIDATED STATEMENT OF INCOME (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
CONDENSED CONSOLIDATED STATEMENT OF INCOME (Unaudited) [Abstract]
Net revenues	$ 99,020	$ 75,764	$ 190,311	$ 132,993
Cost of net revenues	50,710	39,881	100,763	69,427
Gross profit	48,310	35,883	89,548	63,566
Operating expenses:
Technology and development	20,930	16,971	39,438	30,084
Sales and marketing	30,002	24,930	57,040	39,195
General and administrative	15,164	15,522	29,936	28,813
Total operating expenses	66,096	57,423	126,414	98,092
Loss from operations	(17,786)	(21,540)	(36,866)	(34,526)
Interest expense	(156)	0	(308)	0
Interest and other income, net	9	6	16	20
Loss before income taxes	(17,933)	(21,534)	(37,158)	(34,506)
Benefit from income taxes	8,422	17,884	17,607	23,096
Net loss	$ (9,511)	$ (3,650)	$ (19,551)	$ (11,410)
Net loss per share - basic and diluted (in dollars per share)	$ (0.27)	$ (0.11)	$ (0.55)	$ (0.37)
Weighted-average shares outstanding - basic and diluted (in shares)	35,812	33,160	35,506	30,917