Basis of Presentation and Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Percentage of inventory valued using the LIFO method	70.00%		70.00%
Reduction to operating income as a result of adopting new accounting guidance	$ (102)	$ (87)	$ (290)	$ (281)
Accounting Standards Update 2017-07
Reduction to operating income as a result of adopting new accounting guidance		$ 17		$ 60

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

No definition available.

Name:	us-gaap_PercentageOfLIFOInventory
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant