CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenues	$ 56,467	$ 58,544	$ 167,896	$ 161,760
Costs and expenses:
Cost of revenues	22,778	23,061	66,767	64,464
Sales and marketing	23,403	19,047	66,321	56,179
Research and development	11,890	11,351	36,671	38,599
General and administrative	8,382	7,400	24,740	25,307
Change in fair value of contingent consideration	(238)	(2,806)	1,484	(2,806)
Total costs and expenses	66,215	58,053	195,983	181,743
Income (loss) from operations	(9,748)	491	(28,087)	(19,983)
Interest expense	(126)	(241)	(288)	(843)
Gain on sale of a right to use a web domain name			4,800
Other income (expense), net	47	19	26	(88)
Income (loss) before income taxes	(9,827)	269	(23,549)	(20,914)
Provision for (benefit from) income taxes	(9)	1,051	(388)	807
Net loss	$ (9,818)	$ (782)	$ (23,161)	$ (21,721)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.12)	$ (0.01)	$ (0.28)	$ (0.34)
Weighted-average number of common shares used in computing net loss per share attributable to common stockholders, basic and diluted	82,831	78,065	83,335	63,542