Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Apr. 01, 2018		Dec. 31, 2017
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 424,628	[1]	$ 414,038
Accumulated Amortization	(344,594)		(337,155)
Foreign Currency Translation Adjustment	4,379		2,205
Net Carrying Amount	84,413		79,088
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	276,417	[1]	270,877
Accumulated Amortization	(231,266)		(226,190)
Foreign Currency Translation Adjustment	3,214		1,618
Net Carrying Amount	48,365		46,305
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	96,771	[1]	92,741
Accumulated Amortization	(84,940)		(83,585)
Foreign Currency Translation Adjustment	340		171
Net Carrying Amount	12,171		9,327
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	51,120	[1]	50,100
Accumulated Amortization	(28,108)		(27,120)
Foreign Currency Translation Adjustment	825		416
Net Carrying Amount	23,837		23,396
Non-compete Agreements
Finite-Lived Intangible Assets
Gross Carrying Amount	320	[1]	320
Accumulated Amortization	(280)		(260)
Net Carrying Amount	$ 40		$ 60

[1] Gross carrying amount includes $10.9 million of Energid acquired intangible assets.