Restructuring charges - Charges Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3,027	$ 660	$ 12,876	$ 5,688
Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,784	324	12,027	4,011
Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	54	34	232	409
Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	107	241	114	1,141
Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	82	61	503	127
2016 Other Restructuring programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,713		1,713
2016 Other Restructuring programs | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,713		1,713
2016 Other Restructuring programs | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0
2016 Other Restructuring programs | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0
2016 Other Restructuring programs | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0
2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	925		11,279
2016 Manufacturing footprint realignment plan | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	851		10,919
2016 Manufacturing footprint realignment plan | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0
2016 Manufacturing footprint realignment plan | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0
2016 Manufacturing footprint realignment plan | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	74		360
2015 Restructuring programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	58	(74)	48	4,306
2015 Restructuring programs | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(103)	(198)	(502)	3,361
2015 Restructuring programs | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	54	37	232	166
2015 Restructuring programs | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	107	78	200	723
2015 Restructuring programs | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	9	118	56
2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	314	831	(101)	1,497
2014 Manufacturing footprint realignment plan | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	308	619	(118)	831
2014 Manufacturing footprint realignment plan | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	(3)	0	241
2014 Manufacturing footprint realignment plan | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	163	0	389
2014 Manufacturing footprint realignment plan | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6	52	17	36
2014 European restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	17	(97)
2014 European restructuring plan | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	15	(97)
2014 European restructuring plan | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
2014 European restructuring plan | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
2014 European restructuring plan | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2	$ 0
Other restructuring programs - prior years
Restructuring Cost and Reserve [Line Items]
Restructuring charges			(63)	(115)
Other restructuring programs - prior years | Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			15	(181)
Other restructuring programs - prior years | Facility Closure Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			0	2
Other restructuring programs - prior years | Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			(86)	29
Other restructuring programs - prior years | Other Exit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 8	$ 35