DEBT (Net interest and other financing expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Debt Disclosure [Abstract]
Interest expense	$ (190)	[1]	$ (166)	[1]	$ (163)
Interest income	6		6		6
Available-for-sale securities income	8	[2],[3]	3	[2],[3]	0
Other financing costs	(6)		(17)	[4]	(9)
Interest Income (Expense), Net	(182)		(174)		(166)
Normal amortization	13	[5]	14		14
Accelerated amortization	10	[5]	4	[5]	0
Total amortization of financing costs and discounts	$ 23	[5]	$ 18		$ 14

[1] Includes $10 million and $4 million of accelerated amortization for debt issuance costs during 2016 and 2015, respectively.

[2] Investment income relates to the demand deposit and includes interest income as well as dividend income transferred from the equity and corporate bond mutual funds.

[3] Represents investment income related to the restricted investments discussed in Note G.

[4] Includes $9 million related to the early redemption premium payments for the tender and redemption of the 2016 senior notes during 2015.

[5] Accelerated amortization of $10 million for debt issuance costs during 2016 resulted from the combined Ashland and Valvoline financing activities, including the full repayment of the 2015 term loan facility and the $500 million repayment of the 2016 term loan facility. Accelerated amortization of $4 million for debt issuance costs during 2015 resulted from early redemption of the 2016 senior notes and the entrance into the 2015 Senior Credit Agreement.