Revenue Recognition (Deferred Revenue) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	$ 92,090	$ 88,751
Total deferred revenue - long term	3,122	438
Hosted Services - Business
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	88,864	82,892
Total deferred revenue - long term	329	0
Hosted Services - Consumer
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	765	687
Professional Services
Disaggregation of Revenue [Line Items]
Total deferred revenue - short term	2,461	5,172
Total deferred revenue - long term	$ 2,793	$ 438