Business Acquisitions (Details textual) - USD ($) $ in Thousands					3 Months Ended	12 Months Ended
	Nov. 30, 2016	Nov. 04, 2016	Jun. 28, 2016	Nov. 30, 2015	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Jun. 06, 2016	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill					$ 801,406	$ 801,406	$ 596,316		$ 553,335
Goodwill, Acquired During Period						220,795	57,992
DVTEL [Member]
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs				$ 97,500			97,496
Cash acquired							5,015
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net				24,800
Goodwill							60,494
Goodwill, Acquired During Period				58,000	2,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles					1,300
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Tax Assets					1,200
Net tangible assets				12,100			4,025
Identifiable intangible assets				$ 27,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					27,380	27,380	27,380
ISD [Member]
Business Acquisition [Line Items]
Cash acquired								$ 1,800
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net								1,600
Goodwill								$ 1,600
Armasight, Inc. [Member]
Business Acquisition [Line Items]
Cash acquired					2,804	2,804
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			$ 36,000
Goodwill			31,100		32,994	32,994
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			923
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent			2,778		1,855	1,855
Goodwill acquired from acquisitions					1,855	1,855
Total purchase price			43,468
Identifiable intangible assets			$ 7,600		7,600	7,600
Point Grey Research, Inc. [Member]
Business Acquisition [Line Items]
Cash acquired		$ 2,994
Goodwill		183,678
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent		2,438
Total purchase price		259,161
Identifiable intangible assets		$ 39,800
Prox Dynamics, AS [Member]
Business Acquisition [Line Items]
Total purchase price	$ 134,100
Goodwill [Member] | DVTEL [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets and Goodwill, Tax Deduction Amortization Period				15 years
Trade name | DVTEL [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets and Goodwill, Tax Deduction Amortization Period				10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles							$ 3,800
Other Assets [Member] | Prox Dynamics, AS [Member]
Business Acquisition [Line Items]
Intangible assets including goodwill					$ 122,800	$ 122,800