Business Combinations (Schedule of Identifiable Intangible Assets Acquired as Part of Acquisition) (Details) - Avaya Networking $ in Thousands	Jul. 14, 2017 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Amount	$ 44,000
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	6 years
Amount	$ 34,800
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	4 years
Amount	$ 5,300
Trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	5 years
Amount	$ 2,400
Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life (in years)	1 year
Amount	$ 1,500