Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 118,327	$ 94,804	$ 345,823	$ 264,495
Hosted Services - Business
Disaggregation of Revenue [Line Items]
Total revenue	93,234	74,396	271,966	207,832
Hosted Services - Consumer
Disaggregation of Revenue [Line Items]
Total revenue	9,123	7,881	27,944	21,707
Professional Services
Disaggregation of Revenue [Line Items]
Total revenue	$ 15,970	$ 12,527	$ 45,913	$ 34,956