Operating Segments - Reconciliation of Total Reportable Segments' Revenues and EBITDA to Consolidated Revenues and Consolidated Income (Loss) from Continuing Operations Before Taxes (Parenthetical) (Detail) (USD $)	3 Months Ended
	Mar. 29, 2015	Mar. 30, 2014
Tripwire [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Compensation expense	$ 9,200,000	$ 9,200,000
Cost of sales related to adjustment of acquired inventory	300,000
Tripwire [Member] | Consolidated Revenues [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Deferred revenue adjustments	18,400,000
Grass Valley [Member] | Consolidated Revenues [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Deferred revenue adjustments	4,100,000
Grass Valley [Member] | Gross Profit [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Deferred gross profit adjustments	$ 3,300,000