Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Dec. 01, 2017
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill	$ 2,278,512	$ 2,259,177
Currency translation adjustments		6,100
Goodwill Impairment		3,400
Reclassification from indefinite lived intangible assets to definite lived assets	1,717,262	1,524,993
Cloud Tv Reporting Unit
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill Impairment	$ 51,200	3,400
Cloud Tv Reporting Unit | Non-controlling Interest
Schedule Of Goodwill And Intangible Assets [Line Items]
Goodwill Impairment		1,200
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		308,200	$ 308,242
Measurement period adjustments related to Ruckus acquisition		9,800
Acquired intangible assets		$ 494,700	$ 494,700