Employee Stock Plans - Stock-Based Compensation Expense Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 25, 2021	Jun. 26, 2020	Jun. 25, 2021	Jun. 26, 2020	Jun. 26, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		$ 3.7	$ 3.1	$ 7.2	$ 6.2	$ 6.2
Income tax benefit		(0.9)	(0.6)	(1.7)		(1.5)
Stock-based compensation expense, net of tax		2.8	2.5	5.5		4.7
Cost of Revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	[1]	0.4	0.5	0.9		1.0
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation			0.1	0.1		0.1
Sales and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		0.4	0.3	0.7		0.6
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		$ 2.9	$ 2.2	$ 5.5		$ 4.5

[1] Stock-based compensation expense capitalized in inventory for the three and six months ended June 25, 2021 and June 26, 2020was not significant.