Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019	Dec. 29, 2019
Acquired finite-lived intangible assets:
Gross Value	$ 143.2		$ 143.2		$ 139.7
Accumulated Amortization	(110.9)		(110.9)		(107.1)
Net Value	32.3		32.3		32.6
Total intangible assets: gross value	150.1		150.1		146.6
Total intangible assets: net value	39.2		39.2		39.5
Aggregate amortization expense for finite-lived intangible assets	1.8	$ 2.0	3.7	$ 3.5
Trade names
Acquired finite-lived intangible assets:
Indefinite-lived trade names	6.9		6.9		6.9
Customer relationships
Acquired finite-lived intangible assets:
Gross Value	73.0		73.0		72.3
Accumulated Amortization	(54.6)		(54.6)		(53.3)
Net Value	18.4		18.4		19.0
Contracts and backlog
Acquired finite-lived intangible assets:
Gross Value	32.7		32.7		32.0
Accumulated Amortization	(29.7)		(29.7)		(28.4)
Net Value	3.0		3.0		3.6
Developed technology and technical know-how
Acquired finite-lived intangible assets:
Gross Value	26.4		26.4		25.0
Accumulated Amortization	(24.8)		(24.8)		(23.8)
Net Value	1.6		1.6		1.2
Trade names
Acquired finite-lived intangible assets:
Gross Value	1.9		1.9		1.9
Accumulated Amortization	(1.8)		(1.8)		(1.6)
Net Value	0.1		0.1		0.3
In-process research and development
Acquired finite-lived intangible assets:
Gross Value	9.2		9.2		8.5
Accumulated Amortization	0.0		0.0		0.0
Net Value	$ 9.2		$ 9.2		$ 8.5