Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018	Dec. 30, 2018
Acquired finite-lived intangible assets:
Gross Value	$ 128.7		$ 128.7		$ 108.9
Accumulated Amortization	(103.2)		(103.2)		(99.7)
Net Value	25.5		25.5		9.2
Total intangible assets: Gross Value	135.6		135.6		115.8
Total intangible assets: Net Value	32.4		32.4		16.1
Aggregate amortization expense for finite-lived intangible assets	2.0	$ 1.5	3.5	$ 3.2
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	63.8		63.8		52.6
Accumulated Amortization	(51.7)		(51.7)		(50.6)
Net Value	12.1		12.1		2.0
Contracts and backlog
Acquired finite-lived intangible assets:
Gross Value	32.1		32.1		29.9
Accumulated Amortization	(27.3)		(27.3)		(26.4)
Net Value	4.8		4.8		3.5
Developed technology and technical know-how
Acquired finite-lived intangible assets:
Gross Value	25.0		25.0		25.0
Accumulated Amortization	(22.6)		(22.6)		(21.3)
Net Value	2.4		2.4		3.7
Trade names
Acquired finite-lived intangible assets:
Gross Value	1.8		1.8		1.4
Accumulated Amortization	(1.6)		(1.6)		(1.4)
Net Value	0.2		0.2		0.0
In-process research and development
Acquired finite-lived intangible assets:
Gross Value	6.0		6.0		0.0
Accumulated Amortization	0.0		0.0		0.0
Net Value	$ 6.0		$ 6.0		$ 0.0