Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 614		$ 617
Accumulated Amortization	(165)		(157)
Net	449		460
Amortization of intangibles	10	$ 12
Patented technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21		21
Accumulated Amortization	(14)		(14)
Net	7		7
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	511		509
Accumulated Amortization	(109)		(101)
Net	402		408
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	54		58
Accumulated Amortization	(30)		(30)
Net	24		28
Miscellaneous
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	28		29
Accumulated Amortization	(12)		(12)
Net	$ 16		$ 17