CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue		$ 59,334	$ 51,087	$ 119,104	$ 98,915
Costs and expenses (1) (2)
Cost of revenue (3)	[1],[2],[3]	17,887	13,161	34,141	24,896
Sales and marketing	[2],[3]	24,382	20,077	48,676	38,472
General and administrative	[2],[3]	10,471	9,788	20,636	19,286
Product development	[2],[3]	10,109	9,336	19,909	18,287
Restructuring costs	[2],[3]	2,988	0	2,988	0
Amortization of purchased intangibles	[2],[3]	1,178	206	2,490	396
Total costs and expenses	[2],[3]	67,015	52,568	128,840	101,337
Loss from operations		(7,681)	(1,481)	(9,736)	(2,422)
Other income (expense)		229	45	(2)	(38)
Loss before benefit from income taxes		(7,452)	(1,436)	(9,738)	(2,460)
Benefit from income taxes		(2,098)	(224)	(2,326)	(454)
Net loss		$ (5,354)	$ (1,212)	$ (7,412)	$ (2,006)
Basic net (loss) income per common share (in dollars per share)		$ (0.09)	$ (0.02)	$ (0.13)	$ (0.04)
Diluted net (loss) income per common share (in dollars per share)		$ (0.09)	$ (0.02)	$ (0.13)	$ (0.04)
Weighted average shares outstanding used in basic net (loss) income per common share calculation (in shares)		56,491,989	54,189,722	56,392,240	54,766,811
Weighted average shares outstanding used in diluted net (loss) income per common share calculation (in shares)		56,491,989	54,189,722	56,392,240	54,766,811
Stock compensation expense		$ 3,112	$ 3,207	$ 5,906	$ 5,904
Cost of revenue [Member]
Costs and expenses (1) (2)
Amortization of purchased intangibles		839	869	1,679	1,737
Stock compensation expense		476	484	804	844
Depreciation expense		2,323	1,646	4,225	3,044
Sales and marketing expense [Member]
Costs and expenses (1) (2)
Stock compensation expense		937	923	1,532	1,737
Depreciation expense		314	201	565	408
Product development expense [Member]
Costs and expenses (1) (2)
Stock compensation expense		953	931	1,892	1,611
Depreciation expense		209	172	397	349
General and administrative expense [Member]
Costs and expenses (1) (2)
Stock compensation expense		746	869	1,678	1,712
Depreciation expense		$ 236	$ 214	$ 473	$ 414

[1] 3) Amounts include amortization expense as follows: Cost of revenue $839 and $869 for the three months ended June 30, 2015 and 2014, respectively

[2] Amounts include depreciation expense as follows: Cost of revenue $2,323 and $1,646 for the three months ended June 30, 2015 and 2014, respectively and $4,225 and $3,044 for the six months ended June 30, 2015 and 2014, respectively, Sales and marketing $314 and $201 for the three months ended June 30, 2015 and 2014, respectively and $565 and $408 for the six months ended June 30, 2015 and 2014, respectively, Product development $209 and $172 for the three months ended June 30, 2015 and 2014, respectively and $397 and $349 for the six months ended June 30, 2015 and 2014, respectively, and General and administrative $236 and $214 for the three months ended June 30, 2015 and 2014, respectively and $473 and $414 for the six months ended June 30, 2015 and 2014, respectively.

[3] Amounts include stock compensation expense as follows: Cost of revenue $476 and $484 for the three months ended June 30, 2015 and 2014, respectively and $804 and $844 for the six months ended June 30, 2015 and 2014, respectively, Sales and marketing $1,937 and $923 for the three months ended June 30, 2015 and 2014, respectively and $1,532 and $1,737 for the six months ended June 30, 2015 and 2014, respectively, Product development $953 and $931 for the three months ended June 30, 2015 and 2014, respectively and $1,892 and $1,611 for the six months ended June 30, 2015 and 2014, respectively, and General and administrative $746 and $869 for the three months ended June 30, 2015 and 2014, respectively and $1,678 and $1,712 for the six months ended June 30, 2015 and 2014, respectively.