Goodwill and Identified Intangible Assets - Summary of Goodwill and Identified Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 25, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 85,694	$ 85,478
Accumulated Amortization	(84,438)	(81,017)
Total future amortization expense	1,256	4,461
Developed Core Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	30,657	31,707
Accumulated Amortization	(30,657)	(30,757)
Total future amortization expense	$ 0	950
Customer relationships/contracts
Finite-Lived Intangible Assets [Line Items]
Useful Life	4 months 24 days
Gross Carrying Amount	$ 44,715	44,577
Accumulated Amortization	(43,459)	(41,092)
Total future amortization expense	1,256	3,485
Trademarks and Trade Names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	635	609
Accumulated Amortization	(635)	(583)
Total future amortization expense	0	26
Maintenance Agreements and Related Relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,500	5,500
Accumulated Amortization	(5,500)	(5,500)
Total future amortization expense	0	0
Order Backlog
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,137	3,085
Accumulated Amortization	(3,137)	(3,085)
Total future amortization expense	$ 0	$ 0