Cash and Cash Equivalents and Restricted Cash Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017	Apr. 01, 2017	Oct. 01, 2016
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 4,179	$ 4,017
Restricted Cash and Cash Equivalents, Current	11	26
Restricted Cash and Cash Equivalents, Noncurrent	5	21
Cash, Cash Equivalents and Restricted Cash	$ 4,195	$ 4,064	$ 3,925	$ 4,760