Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenues:
Subscription revenues	$ 96,707	$ 70,544	$ 181,890	$ 130,104
Product and other revenues	4,601	3,916	10,446	8,777
Total revenues	101,308	74,460	192,336	138,881
Costs of revenues:
Cost of subscription revenues	14,111	11,228	27,998	22,729
Cost of product and other revenues	1,841	1,280	3,669	2,774
Total cost of revenues	15,952	12,508	31,667	25,503
Gross profit	85,356	61,952	160,669	113,378
Operating expenses:
Technology and development	14,242	9,992	27,910	19,919
Marketing and advertising	30,250	24,490	64,058	46,936
General and administrative	10,111	8,032	19,468	15,774
Amortization of acquired intangible assets	4,297	3,679	8,567	7,358
Total operating expenses	58,900	46,193	120,003	89,987
Income from operations	26,456	15,759	40,666	23,391
Interest and other expense, net	(429)	(1,429)	(536)	(2,573)
Income before income taxes	26,027	14,330	40,130	20,818
Income tax expense	(9,470)	(5,807)	(14,602)	(8,333)
Net income	$ 16,557	$ 8,523	$ 25,528	$ 12,485
Net income per common share:
Basic	$ 0.36	$ 0.20	$ 0.56	$ 0.29
Diluted	$ 0.33	$ 0.18	$ 0.51	$ 0.26
Weighted average common shares outstanding
Basic	45,596	42,764	45,484	42,612
Diluted	49,893	48,015	50,082	47,754