Consolidated Statements Of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Revenue	$ 177,805	$ 157,409	$ 133,089
Costs and expenses:
Cost of revenue	42,555	35,579	33,195
Sales and marketing	62,488	49,614	38,884
General and administrative	39,968	31,606	21,044
Product development	36,397	30,051	20,222
Amortization of purchased intangibles	871	218	109
Total costs and expenses	182,279	147,068	113,454
(Loss) income from operations	(4,474)	10,341	19,635
Other income (expense)	337	376	(485)
(Loss) income before provision for (benefit from) income taxes	(4,137)	10,717	19,150
(Benefit from) provision for income taxes	(638)	4,362	7,112
Net (loss) income	$ (3,499)	$ 6,355	$ 12,038
Basic net income per common share (in dollars per share)	$ (0.06)	$ 0.11	$ 0.23
Diluted net income per common share (in dollars per share)	$ (0.06)	$ 0.11	$ 0.22
Weighted average shares outstanding used in basic net income per common share calculation (in shares)	54,725,236	55,292,597	52,876,999
Weighted average shares outstanding used in diluted net income per common share calculation (in shares)	54,725,236	57,131,041	55,008,742