CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue	$ 60,757	$ 52,787	$ 179,861	$ 151,702
Costs and expenses (1) (2)
Cost of revenue (3)	16,937	13,304	51,078	38,200
Sales and marketing	23,286	20,978	71,962	59,449
General and administrative	7,875	8,787	28,511	28,074
Product development	9,567	9,712	29,476	27,999
Restructuring costs	0	0	2,988	0
Amortization of purchased intangibles	1,193	407	3,683	803
Total costs and expenses	58,858	53,188	187,698	154,525
Income (loss) from operations	1,899	(401)	(7,837)	(2,823)
Other (expense) income	(369)	223	(371)	184
Income (loss) before (benefit from) provision for income taxes	1,530	(178)	(8,208)	(2,639)
(Benefit from) provision for income taxes	(395)	962	(2,721)	507
Net income (loss)	$ 1,925	$ (1,140)	$ (5,487)	$ (3,146)
Basic net (loss) income per common share (in dollars per share)	$ 0.03	$ (0.02)	$ (0.10)	$ (0.06)
Diluted net (loss) income per common share (in dollars per share)	$ 0.03	$ (0.02)	$ (0.10)	$ (0.06)
Weighted average shares outstanding used in basic net (loss) income per common share calculation (in shares)	56,525,647	53,868,124	56,437,198	54,238,536
Weighted average shares outstanding used in diluted net (loss) income per common share calculation (in shares)	57,084,437	53,868,124	56,437,198	54,238,536
Stock compensation expense	$ 2,886	$ 3,654	$ 8,793	$ 9,558
Cost of revenue [Member]
Costs and expenses (1) (2)
Amortization of purchased intangibles	760	921	2,439	2,658
Stock compensation expense	288	365	1,092	1,209
Depreciation expense	2,266	1,732	6,491	4,776
Sales and marketing expense [Member]
Costs and expenses (1) (2)
Stock compensation expense	760	1,030	2,292	2,766
Depreciation expense	254	195	819	603
General and administrative expense [Member]
Costs and expenses (1) (2)
Stock compensation expense	911	1,088	2,590	2,800
Depreciation expense	190	237	663	651
Product development expense [Member]
Costs and expenses (1) (2)
Stock compensation expense	927	1,171	2,819	2,783
Depreciation expense	$ 229	$ 180	$ 626	$ 529