Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands					3 Months Ended		9 Months Ended
	Jan. 02, 2015	Nov. 20, 2014	Jun. 11, 2014	Mar. 31, 2014	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Business Acquisition [Line Items]
Amortization of intangible assets					$ 25,669	$ 15,203	$ 78,090	$ 42,739
Tripwire [Member]
Business Acquisition [Line Items]
Percentage of outstanding shares acquired	100.00%
Acquisition price	$ 703,200
Revolving credit agreement	200,000
Fair value of acquired receivables	37,800
Acquired receivable, gross contractual amount	38,000
Amount of acquired receivables not expected to be collected	$ 200
Post acquisition revenues					30,500		74,500
Post acquisition income (loss) from continuing operations					(10,600)		(46,300)
Amortization of intangible assets					10,600		32,600
Impact on reported revenue due to reduction of acquired deferred revenue balance to fair value					10,900		43,600
Compensation expense							9,200
Amortization of intangible assets, pro forma disclosure						$ 500		2,500
Tripwire [Member] | Pro Forma [Member]
Business Acquisition [Line Items]
Compensation expense								$ 9,200
Coast Wire and Plastic Tech, LLC [Member]
Business Acquisition [Line Items]
Percentage of outstanding shares acquired		100.00%
Acquisition price		$ 36,000
Prosoft Technology, Inc. [Member]
Business Acquisition [Line Items]
Percentage of outstanding shares acquired			100.00%
Acquisition price			$ 104,100
Fair value of acquired receivables			5,900
Acquired receivable, gross contractual amount			6,200
Amount of acquired receivables not expected to be collected			300
Post acquisition revenues					9,800		29,600
Post acquisition income (loss) from continuing operations					400		4,600
Amortization of intangible assets					1,000		3,100
Goodwill acquired			$ 56,900
Period for deducting goodwill for tax purposes			15 years
Grass Valley [Member]
Business Acquisition [Line Items]
Percentage of outstanding shares acquired				100.00%
Acquisition price				$ 218,200
Fair value of acquired receivables				67,400
Acquired receivable, gross contractual amount				77,200
Amount of acquired receivables not expected to be collected				$ 9,800
Post acquisition revenues					70,100		164,600
Post acquisition income (loss) from continuing operations					7,000		(15,200)
Amortization of intangible assets					$ 2,500		$ 7,600