Goodwill and Long-Lived Intangible Assets - Schedule of Purchased Intangible Assets Resulting from Acquisitions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchased Identified Intangible Assets resulting from Acquisitions [Line Items]
Weighted average useful life (years)	4 years 4 months 24 days
Gross carrying amount - Intangible assets	$ 364,992	$ 333,478
Accumulated amortization	$ (241,984)	(210,481)
Weighted remaining average useful life (years)	3 years 9 months 18 days
Net carrying amount - Intangible assets	$ 123,008	122,997
Net carrying amount - Goodwill	$ 403,278	359,841	$ 338,793
Customer Relationships and Other [Member]
Purchased Identified Intangible Assets resulting from Acquisitions [Line Items]
Weighted average useful life (years)	4 years 7 months 6 days
Gross carrying amount - Intangible assets	$ 95,862	88,557
Accumulated amortization	$ (45,862)	(49,527)
Weighted remaining average useful life (years)	3 years 7 months 6 days
Net carrying amount - Intangible assets	$ 50,000	39,030
Existing Technology [Member]
Purchased Identified Intangible Assets resulting from Acquisitions [Line Items]
Weighted average useful life (years)	4 years 1 month 6 days
Gross carrying amount - Intangible assets	$ 196,693	173,543
Accumulated amortization	$ (149,300)	(122,654)
Weighted remaining average useful life (years)	2 years 10 months 25 days
Net carrying amount - Intangible assets	$ 47,393	50,889
Trademarks and Trade Names [Member]
Purchased Identified Intangible Assets resulting from Acquisitions [Line Items]
Weighted average useful life (years)	4 years 10 months 25 days
Gross carrying amount - Intangible assets	$ 72,048	67,701
Accumulated amortization	$ (46,822)	(38,300)
Weighted remaining average useful life (years)	5 years 6 months
Net carrying amount - Intangible assets	$ 25,226	29,401
IPR&D [Member]
Purchased Identified Intangible Assets resulting from Acquisitions [Line Items]
Gross carrying amount - Intangible assets	389	3,677
Net carrying amount - Intangible assets	$ 389	$ 3,677