Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018	Dec. 30, 2018
Acquired finite-lived intangible assets:
Gross Value	$ 135.8		$ 135.8		$ 108.9
Accumulated Amortization	(104.9)		(104.9)		(99.7)
Net Value	30.9		30.9		9.2
Total intangible assets: Gross Value	142.7		142.7		115.8
Total intangible assets: Net Value	37.8		37.8		16.1
Aggregate amortization expense for finite-lived intangible assets	1.7	$ 1.3	5.2	$ 4.5
Trade names
Acquired finite-lived intangible assets:
Gross Value	6.9		6.9		6.9
Accumulated Amortization	0.0		0.0		0.0
Net Value	6.9		6.9		6.9
Customer relationships
Acquired finite-lived intangible assets:
Gross Value	68.9		68.9		52.6
Accumulated Amortization	(52.4)		(52.4)		(50.6)
Net Value	16.5		16.5		2.0
Contracts and backlog
Acquired finite-lived intangible assets:
Gross Value	31.5		31.5		29.9
Accumulated Amortization	(27.7)		(27.7)		(26.4)
Net Value	3.8		3.8		3.5
Developed technology and technical know-how
Acquired finite-lived intangible assets:
Gross Value	25.0		25.0		25.0
Accumulated Amortization	(23.2)		(23.2)		(21.3)
Net Value	1.8		1.8		3.7
Trade names
Acquired finite-lived intangible assets:
Gross Value	1.9		1.9		1.4
Accumulated Amortization	(1.6)		(1.6)		(1.4)
Net Value	0.3		0.3		0.0
In-process research and development
Acquired finite-lived intangible assets:
Gross Value	8.5		8.5		0.0
Accumulated Amortization	0.0		0.0		0.0
Net Value	$ 8.5		$ 8.5		$ 0.0