Consolidated Statements Of Operations - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue		$ 222,779	$ 239,012	$ 209,931
Costs and expenses:
Cost of revenue	[1],[2],[3]	63,161	70,310	52,703
Sales and marketing	[1],[2],[3]	89,529	94,728	83,253
General and administrative	[1],[2],[3]	43,046	37,171	40,192
Product development	[1],[2],[3]	40,198	38,974	37,329
Restructuring costs	[1],[2],[3]	2,369	3,384	0
Amortization of purchased intangibles	[1],[2],[3]	3,885	4,873	1,621
Total costs and expenses	[1],[2],[3]	242,188	249,440	215,098
Loss from operations		(19,409)	(10,428)	(5,167)
Other (expense) income, net		(530)	(202)	(322)
Loss before provision for income taxes		(19,939)	(10,630)	(5,489)
Provision for income taxes		5,934	15,814	1,859
Net loss		$ (25,873)	$ (26,444)	$ (7,348)
Net loss per share of common stock:
Basic (in dollars per share)		$ (0.46)	$ (0.47)	$ (0.13)
Diluted (in dollars per share)		$ (0.46)	$ (0.47)	$ (0.13)
Weighted-average shares used to compute net loss income per share:
Basic (in shares)		56,063,777	56,452,408	54,478,754
Diluted (in shares)		56,063,777	56,452,408	54,478,754
Stock-based compensation expense		$ 9,736	$ 11,814	$ 12,306
Cost Of Revenue [Member]
Costs and expenses:
Amortization of purchased intangibles		2,788	3,167	3,469
Weighted-average shares used to compute net loss income per share:
Stock-based compensation expense		429	1,396	1,492
Depreciation expense		8,234	9,091	6,658
Sales and Marketing [Member]
Weighted-average shares used to compute net loss income per share:
Stock-based compensation expense		2,515	3,088	3,399
Depreciation expense		1,315	1,232	871
General and Administrative [Member]
Weighted-average shares used to compute net loss income per share:
Stock-based compensation expense		3,304	3,692	3,809
Depreciation expense		1,418	893	820
Product Development [Member]
Weighted-average shares used to compute net loss income per share:
Stock-based compensation expense		3,488	3,638	3,606
Depreciation expense		$ 1,044	$ 898	$ 722

[1] Amounts include amortization of purchased intangibles, as follows: Cost of revenue $2,788, $3,167, and $3,469 years ended December 31, 2016, 2015, and 2014, respectively.

[2] Amounts include depreciation expense as follows: Cost of revenue $8,234, $9,091, and $6,658 years ended December 31, 2016, 2015 and 2014, respectively. Sales and marketing $1,315, $1,232 and $871 for the years ended December 31, 2016, 2015 and 2014, respectively. General and administrative $1,418, $893 and $820 for the years ended December 31, 2016, 2015 and 2014, respectively. and Product development $1,044, $898 and $722 for the years ended December 31, 2016, 2015 and 2014, respectively.

[3] Amounts include stock compensation expense as follows: Cost of revenue $429, $1,396, and $1,492 years ended December 31, 2016, 2015 and 2014, respectively. Sales and marketing $2,515, $3,088 and $3,399 for the years ended December 31, 2016, 2015 and 2014, respectively. General and administrative $3,304, $3,692 and $3,809 for the years ended December 31, 2016, 2015 and 2014, respectively. and Product development $3,488, $3,638 and $3,606 for the years ended December 31, 2016, 2015 and 2014, respectively.