Retirement Plans (Schedule of Fair Value of Plan Assets) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 30, 2016	Dec. 29, 2017	Dec. 30, 2016	Sep. 30, 2016	Sep. 25, 2015
Recurring
Defined Benefit Plan Disclosure [Line Items]
Pension plans, weighted-average plan asset allocation		100.00%		100.00%
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year			$ 161.0
Fair value of plan assets at end of year		$ 161.0		$ 161.0
Recurring | U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Pension plans, weighted-average plan asset allocation		1.00%		1.00%
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year			1.7
Fair value of plan assets at end of year		$ 1.7		$ 1.7
Recurring | Diversified Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Pension plans, weighted-average plan asset allocation		92.00%		92.00%
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	[1]		148.3
Fair value of plan assets at end of year	[1]	$ 148.3		$ 148.3
Recurring | Other Assets
Defined Benefit Plan Disclosure [Line Items]
Pension plans, weighted-average plan asset allocation		7.00%		7.00%
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year			11.0
Fair value of plan assets at end of year		$ 11.0		$ 11.0
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation		257.4	27.8	257.4	$ 409.1	$ 375.5
Defined Benefit Plan, Plan Assets, Benefits Paid		(5.3)	(9.4)		(20.1)
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(5.3)	(9.4)		(20.1)
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year		309.5	161.0		309.9
Fair value of plan assets at end of year		161.0	0.0	161.0	309.5	309.9
Defined Benefit Plan, Service Cost		0.8	1.4		1.8	2.4
Interest cost		2.0	2.3		13.2	14.5
Actuarial (gain) loss		(23.2)	(9.0)		65.5
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		125.9	217.0		26.5
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment		0.0	0.0		0.4
Net transfer in		1.1	0.0		0.0
Currency translation		(1.2)	2.1		0.1
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation		47.5	45.6	47.5	50.8	52.2
Defined Benefit Plan, Plan Assets, Benefits Paid			(2.9)	(1.0)	(4.0)
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(1.0)	(2.9)		(4.0)
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year		0.0	0.0	0.0	0.0
Fair value of plan assets at end of year		0.0	0.0	$ 0.0	0.0	0.0
Defined Benefit Plan, Service Cost		0.1	0.0		0.1	0.1
Interest cost		0.4	1.7		2.0	$ 1.9
Actuarial (gain) loss		(2.8)	0.2		0.5
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		0.0	0.9		0.0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment		0.0	0.0		0.0
Net transfer in		0.0	0.0		0.0
Currency translation		$ 0.0	$ 0.0		$ 0.0

[1] Diversified fixed income funds consist of U.S. Treasury bonds, mortgage-backed securities, corporate bonds, asset-backed securities and U.S. agency bonds.