Reportable Segment Information - Summary of Financial Information for Each Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2019	Mar. 31, 2019
Segment Reporting [Abstract]
Accelerated depreciation	$ 20	$ 39

Amount of accelerated depreciation charged against earnings associated with exit from or disposal of business activities or restructuring plan.

No definition available.

Name:	us-gaap_RestructuringReserveAcceleratedDepreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration