Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Dec. 27, 2015
Acquired finite-lived intangible assets:
Gross Value	$ 102.9		$ 185.2
Accumulated Amortization	(82.9)		(155.6)
Net Value	20.0		29.6
Total intangible assets: Gross Value	109.8		192.1
Total intangible assets: Net Value	26.9		36.5
Aggregate amortization expense for finite-lived intangible assets	7.9	$ 10.1
Trade names
Acquired finite-lived intangible assets:
Indefinite-lived trade names	6.9		6.9
Customer relationships
Acquired finite-lived intangible assets:
Gross Value	53.7		83.7
Accumulated Amortization	(43.3)		(67.1)
Net Value	10.4		16.6
Contracts and backlog
Acquired finite-lived intangible assets:
Gross Value	24.7		71.3
Accumulated Amortization	(23.4)		(69.4)
Net Value	1.3		1.9
Developed technology and technical know-how
Acquired finite-lived intangible assets:
Gross Value	23.1		23.1
Accumulated Amortization	(15.1)		(13.3)
Net Value	8.0		9.8
Trade names
Acquired finite-lived intangible assets:
Gross Value	1.4		5.3
Accumulated Amortization	(1.1)		(4.9)
Net Value	0.3		0.4
Favorable operating lease
Acquired finite-lived intangible assets:
Gross Value	0.0		1.8
Accumulated Amortization	0.0		(0.9)
Net Value	$ 0.0		$ 0.9