Segment Information (Summary of Financial Information by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue:
Revenue	$ 91,603	$ 70,959	$ 169,691	$ 137,361
Cost of revenue	27,707	18,049	50,526	36,698
Sales and marketing	34,618	39,343	77,298	72,379
Amortization of purchased intangibles	404	438	809	899
Unallocated corporate expenses	43,320	34,150	88,696	66,769
Loss from operations	(14,446)	(21,021)	(47,638)	(39,384)
Corporate
Revenue:
Unallocated corporate expenses	43,320	34,150	88,696	66,769
Loss from operations	(43,320)	(34,150)	(88,696)	(66,769)
Business | Operating Segments
Revenue:
Revenue	84,016	64,835	155,865	125,830
Cost of revenue	26,085	16,960	47,430	34,622
Sales and marketing	28,926	35,568	66,395	65,660
Amortization of purchased intangibles	404	438	809	899
Loss from operations	28,601	11,869	41,231	24,649
Consumer | Operating Segments
Revenue:
Revenue	7,587	6,124	13,826	11,531
Cost of revenue	1,622	1,089	3,096	2,076
Sales and marketing	5,692	3,775	10,903	6,719
Loss from operations	274	1,260	(173)	2,736
Hosted Services - Business
Revenue:
Revenue	72,382	53,672	133,435	105,209
Hosted Services - Business | Business | Operating Segments
Revenue:
Revenue	72,382	53,672	133,435	105,209
Hosted Services - Consumer
Revenue:
Revenue	7,587	6,124	13,826	11,531
Hosted Services - Consumer | Consumer | Operating Segments
Revenue:
Revenue	7,587	6,124	13,826	11,531
Professional Services
Revenue:
Revenue	11,634	11,163	22,430	20,621
Professional Services | Business | Operating Segments
Revenue:
Revenue	$ 11,634	$ 11,163	$ 22,430	$ 20,621