Segment Information (Summary of Financial Information by Segment) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Revenue:
Revenue		$ 58,241	$ 50,919
Cost of revenue	[1],[2],[3]	13,954	13,781
Sales and marketing	[2],[3]	24,131	21,700
Amortization of purchased intangibles		424	472
Unallocated corporate expenses		23,553	19,890
Loss from operations		(3,821)	(4,924)
Corporate [Member]
Revenue:
Unallocated corporate expenses		23,553	19,890
Loss from operations		(23,553)	(19,890)
Business [Member] | Operating Segments [Member]
Revenue:
Revenue		53,561	46,749
Cost of revenue		12,918	12,906
Sales and marketing		21,723	19,543
Amortization of purchased intangibles		424	472
Loss from operations		18,496	13,828
Consumer [Member] | Operating Segments [Member]
Revenue:
Revenue		4,680	4,170
Cost of revenue		1,036	875
Sales and marketing		2,408	2,157
Loss from operations		1,236	1,138
Hosted Services - Business [Member]
Revenue:
Revenue		47,427	41,493
Hosted Services - Business [Member] | Business [Member] | Operating Segments [Member]
Revenue:
Revenue		47,427	41,493
Hosted Services - Consumer [Member]
Revenue:
Revenue		4,680	4,170
Hosted Services - Consumer [Member] | Consumer [Member] | Operating Segments [Member]
Revenue:
Revenue		4,680	4,170
Professional Services [Member]
Revenue:
Revenue		6,134	5,256
Professional Services [Member] | Business [Member] | Operating Segments [Member]
Revenue:
Revenue		$ 6,134	$ 5,256

[1] Amounts include amortization expense as follows: Cost of revenue $287 thousand and $959 thousand thousand for the three months ended March 31, 2018 and 2017, respectively.Amounts include amortization expense as follows: Cost of revenue and thousand for the three months ended March 31, 2018 and 2017, respectively.

[2] Amounts include depreciation expense as follows: Cost of revenue $1,916 thousand and $1,765 thousand for the three months ended March 31, 2018 and 2017, respectively, Sales and marketing $356 thousand and $381 thousand for the three months ended March 31, 2018 and 2017, respectively, General and administrative $246 thousand and $249 thousand for the three months ended March 31, 2018 and 2017, respectively, and Product development $840 thousand and $398 thousand for the three months ended March 31, 2018 and 2017, respectively. Amounts include depreciation expense as follows: Cost of revenue and $ for the three months ended March 31, 2018 and 2017, respectively, Sales and marketing $ and $ for the three months ended March 31, 2018 and 2017, respectively, General and administrative $ and $ for the three months ended March 31, 2018 and 2017, respectively, and Product development $ and $ for the three months ended March 31, 2018 and 2017, respectively.

[3] Amounts include stock compensation expense as follows: Cost of revenue $154 thousand and $75 thousand for the three months ended March 31, 2018 and 2017, respectively, Sales and marketing $886 thousand and $654 thousand for the three months ended March 31, 2018 and 2017, respectively, General and administrative $840 thousand and $662 thousand for the three months ended March 31, 2018 and 2017, respectively and Product development $558 thousand and $522 thousand for the three months ended March 31, 2018 and 2017, respectively. Amounts include stock compensation expense as follows: Cost of revenue $301 thousand and $342 thousand for the three months ended March 31, 2018 and 2017, respectively, Sales and marketing $1,984 thousand and $1,936 thousand for the three months ended March 31, 2018 and 2017, respectively, General and administrative $2,058 thousand and $2,552 thousand for the three months ended March 31, 2018 and 2017, respectively and Product development $1,760 thousand and $2,770 thousand for the three months ended March 31, 2018 and 2017, respectively.