Business Acquisitions (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Business Acquisition [Line Items]
Increase (decrease) in goodwill from adjustment under purchase accounting	$ (963)
Goodwill acquired during period	85,552
Digital Media
Business Acquisition [Line Items]
Increase (decrease) in goodwill from adjustment under purchase accounting	(1,500)
Digital Media | Operating Segments
Business Acquisition [Line Items]
Increase (decrease) in goodwill from adjustment under purchase accounting	(1,468)
Goodwill acquired during period	44,400
Voice, Backup, Security and CPP
Business Acquisition [Line Items]
Increase (decrease) in goodwill from adjustment under purchase accounting	500
Voice, Backup, Security and CPP | Operating Segments
Business Acquisition [Line Items]
Increase (decrease) in goodwill from adjustment under purchase accounting	505
Goodwill acquired during period	0
Fiscal 2021 Acquisitions
Business Acquisition [Line Items]
Revenue of acquiree since acquisition date	21,300
Total consideration of transactions	135,100
Goodwill acquired during period	85,600
Expected income tax deductible amount	$ 44,100