Goodwill and Other Intangible Assets - Acquisition-Related Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 176,299	$ 196,968
Accumulated Amortization	(143,990)	(132,952)
Net Book Value	32,309	64,016
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	154,301	174,970
Accumulated Amortization	(128,985)	(118,940)
Net Book Value	25,316	56,030
Trademarks, Branding and Domain Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	16,290	16,290
Accumulated Amortization	(9,895)	(9,210)
Net Book Value	6,395	7,080
Acquired Lease Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	5,708	5,708
Accumulated Amortization	(5,110)	(4,802)
Net Book Value	$ 598	$ 906