Goodwill and Intangible Assets (Detail Textuals) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill	$ 2,278,512	$ 2,240,642	$ 2,278,512	$ 2,016,169
Goodwill Impairment		3,400	51,200
Reclassification from indefinite lived intangible assets to definite lived assets	1,717,262	1,348,259	1,717,262
Acquisition accounting adjustments		(29,061)
N&C
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill	573,798	570,852	573,798	$ 624,998
Goodwill Impairment		3,400	51,200
Acquisition accounting adjustments		0
Cloud Tv Reporting Unit
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill Impairment	51,200	1,200
Partial impairment of indefinite-lived intangible assets			3,800
Cloud Tv Reporting Unit | N&C
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill		49,900
Net assets acquired		(15,500)
Cloud Tv Reporting Unit | Non-controlling Interest
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill Impairment	17,900	3,400
In-process R&D
Schedule Of Goodwill And Intangible Assets [Line Items]
Reclassification from indefinite lived intangible assets to definite lived assets		4,100
Ruckus Wireless and ICX Switch business (Ruckus Networks)
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill	$ 318,000	288,973	$ 318,000
Acquired intangible assets		500,700
Acquired additional intangible assets		28,200
Acquisition accounting adjustments		29,100
Net assets acquired		$ 473,192