Earnings (Loss) per Share Schedule of Earnings per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																	12 Months Ended
	Dec. 29, 2017		Sep. 29, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 30, 2016	Sep. 30, 2016		Jun. 24, 2016		Mar. 25, 2016		Dec. 25, 2015		Dec. 29, 2017	Sep. 30, 2016	Sep. 25, 2015
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ 1,607.4		$ 64.3		$ 70.6		$ 28.9		$ (176.8)	$ 110.0		$ 176.7		$ 98.5		$ 103.8		$ 1,771.2	$ 489.0	$ 236.6
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									0.0									0.0	0.0	2.0
Income (Loss) From Continuing Operations Attributable To Common Stockholders									(176.8)									1,771.2	489.0	234.6
Income (loss) from discontinued operations, net of income taxes	$ 1.3		$ (0.6)		$ (7.8)		$ 370.3		23.6	$ 5.0		$ 22.6		$ 19.8		$ 107.3		363.2	154.7	88.1
Income (Loss) From Discontinued Operations Attributable To Common Stockholders									0.0									0.0	0.0	0.7
Net Income (Loss) Available to Common Stockholders, Basic									23.6									363.2	154.7	87.4
Net Income (Loss) Available to Common Stockholders, Basic									$ (153.2)									$ 2,134.4	$ 643.7	$ 322.0
Weighted Average Number of Shares Outstanding, Basic									105.7							115.4		97.7	110.6	115.8
Weighted Average Number of Shares Outstanding, Diluted									0.0									0.2	0.9	1.4
Weighted Average Number of Shares Outstanding, Diluted									105.7							116.3		97.9	111.5	117.2
Income (Loss) from Continuing Operations, Per Basic Share	$ 17.43	[1]	$ 0.66	[1]	$ 0.72	[1]	$ 0.28	[1]	$ (1.67)	$ 1.02	[1]	$ 1.63	[1]	$ 0.89	[1]	$ 0.90	[1]	$ 18.13	$ 4.42	$ 2.03
Income (Loss) from Discontinued Operations, Per Basic Share									0.22							0.93		3.72	1.40	0.75
Earnings Per Share, Basic									(1.45)							1.83		21.85	5.82	2.78
Income (Loss) from Continuing Operations, Per Diluted Share	$ 17.40	[1]	$ 0.66	[1]	$ 0.72	[1]	$ 0.28	[1]	(1.67)	$ 1.01	[1]	$ 1.62	[1]	$ 0.88	[1]	0.89	[1]	18.09	4.39	2.00
Income (Loss) from Discontinued Operations, Per Diluted Share									0.22							0.92		3.71	1.39	0.75
Earnings Per Share, Diluted									$ (1.45)							$ 1.82		$ 21.80	$ 5.77	$ 2.75

[1] Quarterly and annual computations are prepared independently. Therefore, the sum of each quarter may not necessarily total the fiscal period amounts noted elsewhere within this Annual Report on Form 10-K.