Description of Business and Summary of Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	$ 88,751	$ 55,015
Total deferred revenue - long term	438	222
Hosted Services - Business
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	82,892	51,689
Total deferred revenue - long term	0	19
Hosted Services - Consumer
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	687	543
Professional Services - Business
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	5,172	2,783
Total deferred revenue - long term	$ 438	$ 203