Restructuring and other strategic initiatives - Income Statement Location (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Restructuring Cost and Reserve
Restructuring expenses	$ 1.9	$ 8.7	$ 8.6	$ 32.9
—Impairment of fixed assets	0.0	1.4	0.0	5.1
Total expenses related to other strategic initiatives	0.2	3.3	0.5	4.7
European Office And Distribution Center
Restructuring Cost and Reserve
Severance-related expenses (included in cost of sales)	0.8		3.7
Korean Facility
Restructuring Cost and Reserve
—Impairment of fixed assets		4.8		4.8
Restructuring expenses:
Restructuring Cost and Reserve
Restructuring expenses	1.9	7.3	8.5	26.4
—Severance expenses included in cost of sales
Restructuring Cost and Reserve
Severance-related expenses (included in cost of sales)	0.0	0.3	0.0	0.9
—Severance expenses included in SG&A
Restructuring Cost and Reserve
Severance-related expenses (included in cost of sales)	0.2	3.0	0.5	3.8
—Severance expenses | Korean Facility
Restructuring Cost and Reserve
Severance-related expenses (included in cost of sales)		12.8		12.8
—Severance expenses | Restructuring expenses:
Restructuring Cost and Reserve
Restructuring expenses	0.1	3.3	1.0	17.1
—Non-severance labor and benefit expenses | Restructuring expenses:
Restructuring Cost and Reserve
Restructuring expenses	0.2	1.8	1.6	2.6
—Consulting expenses | Restructuring expenses:
Restructuring Cost and Reserve
Restructuring expenses	0.4	0.3	1.9	1.2
—Other restructuring expenses | Restructuring expenses:
Restructuring Cost and Reserve
Restructuring expenses	1.2	1.9	4.0	5.5
—Impairment of inventory
Restructuring Cost and Reserve
Restructuring expenses	$ 0.0	0.0	$ 0.1	1.4
—Impairment of inventory | Korean Facility
Restructuring Cost and Reserve
Restructuring expenses		$ 1.4		$ 1.4