Accounts Receivable - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sold to financial institutions	$ 129	$ 50
Ashland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable sold to financial institutions		40
Aggregate accounts receivable sold by Ashland to financial institutions		$ 90