Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2016
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		$ 94	$ 55		$ 48
Additions Charged to Expense		17	7		9
Additions Charged to Other Accounts		7	39		13
Other Changes	[1]	(27)	(7)		(15)
Balance at End of Period		91	94		55
Allowance for Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		108	165		112
Additions Charged to Expense		3	6		1
Additions Charged to Other Accounts		4	7		52	[2]
Other Changes	[1]	(10)	(70)	[3]	0
Balance at End of Period		$ 105	$ 108		$ 165

[1] Other changes related to allowance for doubtful accounts primarily includes write-offs of uncollectible trade receivables, net of recoveries. Other Changes also includes the impact of foreign currency translation adjustments.

[2] The increase in the valuation allowance was primarily due to the loss recorded on the exit from the Energy-from-Waste business. These costs were recorded in discontinued operations. See Note 3, Discontinued Operations, for additional information.

[3] The decrease in the valuation allowance was primarily due to the utilization of federal and state loss carryforwards as a result of recognizing the gain on the sale of our PMD business. This benefit was recorded in discontinued operations. See Note 3, Discontinued Operations, for additional information.