Segment Information - Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Total revenue	$ 118,327	$ 94,804	$ 345,823	$ 264,495
Cost of revenue	38,795	27,692	112,377	78,218
Sales and marketing	40,852	32,775	116,427	110,073
Amortization of purchased intangibles	488	411	1,237	1,219
Unallocated corporate expenses	58,971	69,069	163,768	157,765
Loss from operations	(20,779)	(35,143)	(47,986)	(82,780)
Corporate
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Cost of revenue	0	0	0	0
Sales and marketing	0	0	0	0
Amortization of purchased intangibles	0	0	0	0
Unallocated corporate expenses	58,971	69,069	163,768	157,765
Loss from operations	(58,971)	(69,069)	(163,768)	(157,765)
Business | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	109,204	86,923	317,879	242,788
Cost of revenue	37,057	25,862	106,932	73,291
Sales and marketing	34,640	27,525	96,758	93,920
Amortization of purchased intangibles	488	411	1,237	1,219
Unallocated corporate expenses	0	0	0	0
Loss from operations	37,019	33,125	112,952	74,358
Consumer | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	9,123	7,881	27,944	21,707
Cost of revenue	1,738	1,830	5,445	4,927
Sales and marketing	6,212	5,250	19,669	16,153
Amortization of purchased intangibles	0	0	0	0
Unallocated corporate expenses	0	0	0	0
Loss from operations	1,173	801	2,830	627
Hosted Services - Business
Segment Reporting Information [Line Items]
Total revenue	93,234	74,396	271,966	207,832
Hosted Services - Business | Corporate
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Hosted Services - Business | Business | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	93,234	74,396	271,966	207,832
Hosted Services - Business | Consumer | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Hosted Services - Consumer
Segment Reporting Information [Line Items]
Total revenue	9,123	7,881	27,944	21,707
Hosted Services - Consumer | Corporate
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Hosted Services - Consumer | Business | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Hosted Services - Consumer | Consumer | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	9,123	7,881	27,944	21,707
Professional Services
Segment Reporting Information [Line Items]
Total revenue	15,970	12,527	45,913	34,956
Professional Services | Corporate
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Professional Services | Business | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	15,970	12,527	45,913	34,956
Professional Services | Consumer | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	$ 0	$ 0	$ 0	$ 0