Goodwill and Intangible Assets, Net - Acquisition-Related Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 497,076	$ 310,590
Accumulated Amortization	(211,930)	(191,990)
Net Book Value	285,146	118,600
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	418,707	263,720
Accumulated Amortization	(185,129)	(167,664)
Net Book Value	233,578	96,056
Trademarks, Branding and Domain Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	64,271	32,772
Accumulated Amortization	(13,440)	(11,702)
Net Book Value	50,831	21,070
Noncompetition Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	8,390	8,390
Accumulated Amortization	(7,806)	(7,107)
Net Book Value	584	1,283
Acquired Lease Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	5,708	5,708
Accumulated Amortization	(5,555)	(5,517)
Net Book Value	$ 153	$ 191