Revenue from Contract with Customer (Schedule of Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 469,624	$ 366,620	$ 291,609
Hosted Services - Business
Disaggregation of Revenue [Line Items]
Revenue	364,231	286,588	225,705
Hosted Services - Consumer
Disaggregation of Revenue [Line Items]
Revenue	37,695	29,764	24,480
Professional Services - Business
Disaggregation of Revenue [Line Items]
Revenue	$ 67,698	$ 50,268	$ 41,424

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details