Segment Information (Summary of Financial Information by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Revenue:
Revenue	$ 66,402	$ 58,241
Cost of revenue	18,649	13,954
Sales and marketing	33,036	24,131
Amortization of purchased intangibles	461	424
Unallocated corporate expenses	32,619	23,553
Loss from operations	(18,363)	(3,821)
Corporate
Revenue:
Unallocated corporate expenses	32,619	23,553
Loss from operations	(32,619)	(23,553)
Business \| Operating Segments
Revenue:
Revenue	60,995	53,561
Cost of revenue	17,662	12,918
Sales and marketing	30,092	21,723
Amortization of purchased intangibles	461	424
Loss from operations	12,780	18,496
Consumer \| Operating Segments
Revenue:
Revenue	5,407	4,680
Cost of revenue	987	1,036
Sales and marketing	2,944	2,408
Loss from operations	1,476	1,236
Hosted Services - Business
Revenue:
Revenue	51,537	47,427
Hosted Services - Business \| Business \| Operating Segments
Revenue:
Revenue	51,537	47,427
Hosted Services - Consumer
Revenue:
Revenue	5,407	4,680
Hosted Services - Consumer \| Consumer \| Operating Segments
Revenue:
Revenue	5,407	4,680
Professional Services
Revenue:
Revenue	9,458	6,134
Professional Services \| Business \| Operating Segments
Revenue:
Revenue	$ 9,458	$ 6,134

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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The aggregate cost of goods produced and sold and services rendered during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The aggregate total amount of expenses directly related to the marketing or selling of products or services.

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