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Related Party Transactions (Details) - USD ($) $ in Millions		3 Months Ended
	Mar. 25, 2019	Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Powersem
Related Party Transaction [Line Items]
Revenue from related parties		$ 0.1
Purchase from related party		0.8	$ 1.1
Receivable from related parties		0.1		$ 0.1
Payables to related parties		0.1		0.2
EB Tech
Related Party Transaction [Line Items]
Payables to related parties		0.1
Amount of transaction		0.1
ATEC
Related Party Transaction [Line Items]
Payables to related parties		0.4		$ 0.5
Amount of transaction		$ 1.5	$ 2.4
MWT
Related Party Transaction [Line Items]
Loss on disposal	$ 2.6
Powersem
Related Party Transaction [Line Items]
Ownership percentage		45.00%
EB Tech
Related Party Transaction [Line Items]
Ownership percentage		20.00%
ATEC
Related Party Transaction [Line Items]
Ownership percentage		24.00%