INCOME TAXES (Income from continuing operations, before tax and reconciliation of provision) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
United States	[1]	$ (152)		$ (158)		$ (364)	[2]
Foreign		288		327		248	[2]
Total Income (loss) from continuing operations before income taxes		136		169		(116)
Income taxes computed at U.S. statutory rate (35%)		47		59		(40)
Net gain on divestitures		0		11		37
Uncertain tax positions		27		23		33
Valuation allowance charges		43	[3]	(29)		14
Claim for research and development credits		(10)	[4]	(7)	[4]	(2)
State taxes		2	[5]	(8)		(16)	[5]
Goodwill impairment		55	[6]	0		0
Net impact of foreign results		(32)		(73)		(214)	[7]
Other items	[8]	1		2		0
Income tax expense (benefit)		$ 133		(22)		(188)
Federal statutory income tax rate		35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount		$ 24
Effective Income Tax Rate Reconciliation, Change in State Deferred Tax Assets Valuation Allowance, Amount		19
Deferred tax adjustments, primarily related to state taxes		(3)				5
Deferred Tax Liabilities, Undistributed Foreign Earnings						168
Change in foreign tax rate adjustment						14
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Separation Costs		11
Effective Income Tax Reconciliation, Tax Settlement, Other, Key Items Amount						32
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Key Items Amount						7
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on divestitures		$ 0		$ 11		37
Water Technologies [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Net gain on divestitures						39
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on divestitures						$ 39

[1] A significant component of the fluctuations within this caption relates to the annual remeasurements of the U.S. pension and other postretirement plans.

[2] For 2014, the United States and Foreign amounts for income (loss) from continuing operations before income taxes have been revised to reflect a change in the classification of the elimination of foreign intercompany dividends. There was no impact on the total loss from continuing operations before income taxes or on the computation of income tax expense (benefit) for the year end September 30, 2014 and therefore Ashland does not believe that this revision is material to the previously filed financial information.

[3] Related to foreign tax credit carryforward of $24 million and state deferred tax asset valuation allowances of $19 million during 2016.

[4] 2016 and 2015 includes a tax benefit related to credits signed into law on a retroactive basis.

[5] 2016 includes a $3 million benefit and 2014 includes an expense of $5 million recorded for deferred tax adjustments, primarily attributable to state rate changes.

[6] 2016 includes tax expense related to nondeductible goodwill impairment.

[7] 2014 includes a $168 million tax benefit related to the reversal of deferred tax liabilities for outside basis differences and other related matters and a $14 million expense recorded for a rate change in a foreign jurisdiction.

[8] Other items principally includes permanent items in all periods presented, specifically, 2016 includes expense of $11 million for nondeductible transaction costs associated with the separation of Valvoline.