Business Acquisitions (Detail) - USD ($) $ in Thousands			9 Months Ended
	Nov. 30, 2016	Nov. 04, 2016	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 930,846			$ 801,406
Point Grey Research, Inc. [Member]
Business Acquisition [Line Items]
Cash acquired		$ 2,994
Other tangible assets and liabilities, net		35,064
Net deferred taxes		2,438
Identifiable Intangible assets		39,800
Goodwill		183,741
Total purchase price		$ 259,161
Prox Dynamics, AS [Member]
Business Acquisition [Line Items]
Cash acquired			11,706
Other tangible assets and liabilities, net			(900)
Net deferred taxes				$ (7,387)
Identifiable Intangible assets					$ 31,400
Goodwill				$ 99,269	$ 91,900	$ 122,800
Total purchase price	$ 134,088		$ 134,088