Accumulated Other Comprehensive Income (Schedule of Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 30, 2016	Dec. 29, 2017		Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized loss on derivatives	$ 0.2	$ 1.3		$ 0.7
Income tax provision	0.0	(0.3)		(0.2)
Net of income taxes	0.2	1.0		0.5
Amortization of pension and post-retirement benefit plans:
Net actuarial loss	1.0	2.7	[1]	11.4
Prior service credit	(0.6)	(1.9)	[1]	(2.7)
Plan settlements	45.0	70.2	[1]	8.1
Total before tax	45.4	67.9		17.6
Income tax provision	(16.7)	(27.3)		(6.5)
Net of income taxes	28.7	40.6		11.1
Total reclassifications for the period	28.9	36.9		(47.8)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	0.0	(3.1)		0.8
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	$ 0.0	$ (4.7)		$ (59.4)

[1] These accumulated other comprehensive income components are included in the computation of net periodic benefit cost. See Note 14 for additional details.