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Related Party Transactions (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Apr. 26, 2019	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Related Party Transaction
Cost method investments		$ 0.5		$ 0.5
MWT
Related Party Transaction
Loss on disposal	$ 2.6
Powersem
Related Party Transaction
Ownership percentage (percent)		45.00%		45.00%
Revenue from related parties		$ 0.4	$ 0.2	$ 1.1	$ 0.4
Purchase from related party		0.8	0.8	1.8	2.4
Receivable from related parties		0.1		0.1		$ 0.0
Payables to related parties		$ 0.1		$ 0.1		0.2
EB Tech
Related Party Transaction
Ownership percentage (percent)		19.00%		19.00%
Revenue from related parties		$ 0.0	0.0	$ 0.0	0.0
Purchase from related party		0.0	0.1	0.0	0.3
Receivable from related parties		0.0		0.0		0.0
Payables to related parties		$ 0.0		$ 0.0		0.0
ATEC
Related Party Transaction
Ownership percentage (percent)		24.00%		24.00%
Revenue from related parties		$ 0.0	0.0	$ 0.0	0.0
Purchase from related party		2.4	$ 1.7	5.8	$ 5.5
Receivable from related parties		0.0		0.0		0.0
Payables to related parties		$ 0.1		$ 0.1		$ 0.1