Restructuring charges - Manufacturing Footprint Realignment Plans (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 25, 2016	Sep. 25, 2016	Apr. 30, 2014
2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 2.8	$ 15.5
2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	2.8	6.8
Employee termination benefits | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0.9	11.3
Accelerated Depreciation And Other Costs | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	1.9	4.2
Accelerated Depreciation And Other Costs | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	2.5	6.9
Minimum | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	34.0	34.0
Restructuring costs expected cash payment	27.0	27.0
Minimum | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	43.0	43.0	$ 37.0
Restructuring costs expected cash payment	33.0	33.0	26.0
Expected aggregate capital expenditures	24.0	24.0
Minimum | Employee termination benefits | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	14.0	14.0
Minimum | Employee termination benefits | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	11.0	11.0
Minimum | Facility closure and other exit costs | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2.0	2.0
Minimum | Facility closure and other exit costs | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	1.0	1.0
Minimum | Accelerated Depreciation Charges | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	10.0	10.0
Minimum | Accelerated Depreciation Charges | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	10.0	10.0
Minimum | Other | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	8.0	8.0
Minimum | Other | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	21.0	21.0
Maximum | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	44.0	44.0
Restructuring costs expected cash payment	31.0	31.0
Maximum | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	48.0	48.0	44.0
Restructuring costs expected cash payment	38.0	38.0	$ 31.0
Expected aggregate capital expenditures	30.0	30.0
Maximum | Employee termination benefits | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	15.0	15.0
Maximum | Employee termination benefits | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	12.0	12.0
Maximum | Facility closure and other exit costs | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	3.0	3.0
Maximum | Facility closure and other exit costs | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2.0	2.0
Maximum | Accelerated Depreciation Charges | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	13.0	13.0
Maximum | Accelerated Depreciation Charges | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	10.0	10.0
Maximum | Other | 2016 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	13.0	13.0
Maximum | Other | 2014 Manufacturing footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	$ 24.0	$ 24.0