Goodwill and Other Intangible Assets - Acquisition-Related Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 172,824	$ 196,968
Accumulated Amortization	(147,394)	(132,952)
Net Book Value	25,430	64,016
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	150,826	174,970
Accumulated Amortization	(132,123)	(118,940)
Net Book Value	18,703	56,030
Trademarks, Branding and Domain Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	16,290	16,290
Accumulated Amortization	(10,063)	(9,210)
Net Book Value	6,227	7,080
Acquired Lease Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	5,708	5,708
Accumulated Amortization	(5,208)	(4,802)
Net Book Value	$ 500	$ 906