Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 28, 2021	Mar. 29, 2020	Dec. 27, 2020
Acquired finite-lived intangible assets:
Gross Value	$ 150.0		$ 150.0
Accumulated Amortization	(115.3)		(113.9)
Net Value	34.7		36.1
Total intangible assets: gross value	156.9		156.9
Total intangible assets: net value	41.6		43.0
Aggregate amortization expense for finite-lived intangible assets	1.4	$ 1.9
Trade names
Acquired finite-lived intangible assets:
Indefinite-lived trade names	6.9		6.9
Customer relationships
Acquired finite-lived intangible assets:
Gross Value	75.3		75.3
Accumulated Amortization	(56.2)		(55.7)
Net Value	19.1		19.6
Contracts and backlog
Acquired finite-lived intangible assets:
Gross Value	33.4		33.4
Accumulated Amortization	(31.7)		(31.0)
Net Value	1.7		2.4
Developed technology and technical know-how
Acquired finite-lived intangible assets:
Gross Value	29.9		29.9
Accumulated Amortization	(25.4)		(25.3)
Net Value	4.5		4.6
Trade names
Acquired finite-lived intangible assets:
Gross Value	2.0		2.0
Accumulated Amortization	(2.0)		(1.9)
Net Value	0.0		0.1
In-process research and development
Acquired finite-lived intangible assets:
Gross Value	9.4		9.4
Accumulated Amortization	0.0		0.0
Net Value	$ 9.4		$ 9.4

Intangible Assets (Excluding Goodwill), Gross

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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