Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Deferred tax assets
Federal net operating loss carryforwards	$ 0	$ 96
Non-U.S. net operating loss carryforwards	2	1
State net operating loss carryforwards	19	28
Employee benefit obligations	86	132
Compensation accruals	21	29
Credit carryforwards	36	13
Other	9	13
Valuation allowances	(7)	(8)
Net deferred tax assets	166	304
Deferred tax liabilities
Goodwill and other intangibles	3	3
Property, plant and equipment	23	17
Undistributed earnings	2	3
Total deferred tax liabilities	28	23
Total net deferred tax assets	138	$ 281
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	5
Expiration Years 2020 Through 2033 | Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	7
Expiration Years 2019 Through 2037 | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 481