Receivables, Net - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net receivables due from equity affiliates	$ 64		$ 42
Sales under factoring agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash generated under factoring agreements	146	$ 98
Cash provided by operating activities	$ (8)	$ 38