Restructuring Costs - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring charges before benefit		$ 2,800
Restructuring costs	[1],[2],[3]	2,369	$ 3,384	$ 0
Restructuring liability		2,551	1,328	$ 0
Contract termination costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs		$ (384)	$ 1,745

[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.