Business Acquisitions (Detail) - USD ($) $ in Thousands	Nov. 04, 2016	Jun. 28, 2016	Dec. 31, 2016	Dec. 31, 2015	Nov. 30, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill			$ 801,406	$ 596,316		$ 553,335
Armasight, Inc. [Member]
Business Acquisition [Line Items]
Cash acquired			2,804
Other tangible assets and liabilities, net			1,925
Net deferred taxes		$ (2,778)	(1,855)
Identifiable intangible assets		7,600	7,600
Goodwill		31,100	32,994
Total purchase price		$ 43,468
DVTEL [Member]
Business Acquisition [Line Items]
Cash acquired				5,015
Net tangible assets				4,025	$ 12,100
Net deferred taxes				582
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 27,380	27,380
Purchase price				97,496	97,500
Identifiable intangible assets					$ 27,400
Goodwill				$ 60,494
Point Grey Research, Inc. [Member]
Business Acquisition [Line Items]
Cash acquired	$ 2,994
Other tangible assets and liabilities, net	35,127
Net deferred taxes	(2,438)
Identifiable intangible assets	39,800
Goodwill	183,678
Total purchase price	$ 259,161