Acquisitions (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Sep. 30, 2018	Jan. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Contingent earn-out consideration in cash	$ 1,800		$ 1,800	$ 0
Goodwill acquired in acquisition			5,010
Conversable, Inc.
Business Acquisition [Line Items]
Aggregate purchase price	6,600
Cash payment in acquisition	1,200
Equity consideration in acquisition	3,000
Contingent earn-out consideration in cash	1,800		1,800
Contingent earn-out consideration in equity	300		$ 300
Deferred revenue in acquisition	300
Goodwill acquired in acquisition	5,000
Aggregate amount of intangibles acquired	1,600
Potential earn-out consideration payments based on achieving targets	2,100
Potential earn-out consideration payments for compensation	$ 600
Period for recognizing compensation-related potential earn-out consideration payments	12 months
BotCentral
Business Acquisition [Line Items]
Equity consideration in acquisition		$ 1,000
Aggregate amount of intangibles acquired		1,200
Acquisition costs		$ 200