Income Taxes (Schedule of Significant Components of Income Taxes Related to Continuing Operations) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 30, 2016	Dec. 25, 2015	Dec. 29, 2017	Sep. 30, 2016	Sep. 25, 2015
Current:
U.K.	$ 0.0		$ 0.4	$ 0.3	$ 0.2
Non-U.K.	82.0		37.7	120.5	67.3
Current income tax provision	82.0		38.1	120.8	67.5
Deferred:
U.K.	(0.5)		0.6	0.7	(0.8)
Non-U.K.	(203.2)		(1,748.3)	(377.1)	(196.0)
Deferred income tax benefit	(203.7)		(1,747.7)	(376.4)	(196.8)
Provision for (benefit from) income taxes	$ (121.7)	$ (37.3)	$ (1,709.6)	$ (255.6)	$ (129.3)