Basis of Presentation and Significant Accounting Policies Update Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Millions	Oct. 01, 2018	Mar. 31, 2019	Sep. 30, 2018	Mar. 25, 2018	Sep. 24, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings	$ 1,382	$ 3,309	$ 542
Restricted cash and cash equivalents		$ 0		$ 2,000
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings	50
Reclassifications from accumulated other comprehensive income	50
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings	$ 2,600
Other Noncurrent Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash and cash equivalents				$ 2,000	$ 2,000