Ashland (ASH) 10-Q 1 May 19 2019 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information	6 Months Ended
	Mar. 31, 2019shares
Document And Entity Information [Abstract]
Entity Registrant Name	ASHLAND GLOBAL HOLDINGS INC.
Entity Central Index Key	0001674862
Current Fiscal Year End Date	--09-30
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	62,712,232
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	ASH
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019

STATEMENTS OF CONSOLIDATED COMP

STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Sales	$ 667	$ 672	$ 1,243	$ 1,253
Cost of sales	469	449	893	851
Gross profit	198	223	350	402
Selling, general and administrative expense	136	146	279	300
Research and development expense	17	18	34	37
Equity and other income (loss)	(1)	4	0	2
Operating income (loss)	44	63	37	67
Net interest and other expense (income)	(3)	24	52	49
Other net periodic benefit income (loss)	(1)	1	17	1
Net income (loss) on divestitures	0	0	(3)	(1)
Income (loss) from continuing operations before income taxes	46	40	(1)	18
Income tax expense (benefit)	1	(2)	25	8
Income (loss) from continuing operations	45	42	(26)	10
Income from discontinued operations (net of income taxes)	31	31	54	59
Net income (loss)	$ 76	$ 73	$ 28	$ 69
Basic earnings per share - Note L
Income (loss) from continuing operations	$ 0.72	$ 0.66	$ (0.41)	$ 0.15
Income from discontinued operations	0.49	0.51	0.86	0.95
Net income (loss)	1.21	1.17	0.45	1.10
Diluted earnings per share - Note L
Income (loss) from continuing operations	0.71	0.65	(0.41)	0.15
Income from discontinued operations	0.48	0.50	0.86	0.93
Net income (loss)	$ 1.19	$ 1.15	$ 0.45	$ 1.08
COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ 76	$ 73	$ 28	$ 69
Other comprehensive income (loss), net of tax
Unrealized translation gain (loss)	(9)	55	(40)	58
Pension and postretirement obligation adjustment	0	0	(6)	0
Net change in investment securities	0	(6)	0	2
Other comprehensive income (loss)	(9)	49	(46)	60
Comprehensive income (loss)	$ 67	$ 122	$ (18)	$ 129

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Millions		Mar. 31, 2019	Sep. 30, 2018
Current assets
Cash and cash equivalents		$ 164	$ 294
Accounts receivable	[1]	522	522
Inventories - Note F		599	596
Other assets		63	60
Held for sale - Note B		739	240
Total current assets		2,087	1,712
Property, plant and equipment
Cost		3,167	3,172
Accumulated depreciation		1,580	1,526
Net property, plant and equipment		1,587	1,646
Goodwill - Note G		2,279	2,304
Intangibles - Note G		1,135	1,185
Restricted investments - Note E		296	312
Asbestos insurance receivable - Note K		175	179
Deferred income taxes		28	28
Other assets		411	416
Held for sale - Note B			477
Total noncurrent assets		5,911	6,547
Total assets		7,998	8,259
Current liabilities
Short-term debt - Note H		261	254
Trade and other payables		280	331
Accrued expenses and other liabilities		232	328
Held for sale - Note B		147	163
Total current liabilities		920	1,076
Noncurrent liabilities
Long-term debt - Note H		2,275	2,275
Asbestos litigation reserve - Note K		587	612
Deferred income taxes		283	286
Employee benefit obligations - Note J		145	156
Other liabilities		426	422
Held for sale - Note B			26
Total noncurrent liabilities		3,716	3,777
Commitments and contingencies - Note K
Stockholders’ equity - Note M		3,362	3,406
Total liabilities and stockholders' equity		$ 7,998	$ 8,259
[1]	Accounts receivable includes an allowance for doubtful accounts of $3 million at both March 31, 2019 and September 30, 2018.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Current assets
Allowance for doubtful accounts	$ 3	$ 3

STATEMENT OF CONSOLIDATED EQUIT

STATEMENT OF CONSOLIDATED EQUITY (unaudited) - 6 months ended Mar. 31, 2019 - USD ($) $ in Millions		Total	Common stock [Member]	Paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss) [Member]	[1]
Beginning Balance at Sep. 30, 2018		$ 3,406	$ 1	$ 946	$ 2,750	$ (291)
Adoption of new accounting pronouncements	[2]				34	(34)
Total comprehensive income (loss)
Net income (loss)		28			28
Other comprehensive income (loss)		(46)				(46)
Regular dividends, $0.50 per common share		(32)			(32)
Common shares issued under stock incentive and other plans	[3]	6		6
Ending Balance at Mar. 31, 2019		$ 3,362	$ 1	$ 952	$ 2,780	$ (371)
[1]	At March 31, 2019 and September 30, 2018, the after-tax accumulated other comprehensive loss attributable to Ashland of $371 million and $291 million, respectively, was each comprised of net unrealized translation losses of $368 million and $328 million, respectively, net unrealized gains on investment securities of zero and $34 million, respectively, and unrecognized prior service costs as a result of certain employee benefit plan amendments of $3 million and unrecognized prior services credits of $3 million, respectively.
[2]	Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and the tax effects of intercompany transfers during fiscal 2019. See Note A for more information.
[3]	Common shares issued were 234,352 for the six months ended March 31, 2019.

STATEMENT OF CONSOLIDATED EQU_2

STATEMENT OF CONSOLIDATED EQUITY (unaudited) (Parenthetical) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
Statement Of Stockholders Equity [Abstract]
Dividend per common share	$ 0.50
Accumulated other comprehensive loss	$ (371)	$ (291)
Unrecognized prior service costs (credits)	3	(3)
Net unrealized translation loss	(368)	(328)
Investment securities unrealized gain	$ 0	$ 34
Common shares issued (in shares)	234,352

STATEMENTS OF CONDENSED CONSOLI

STATEMENTS OF CONDENSED CONSOLIDATED CASH FLOWS (unaudited) - USD ($) $ in Millions		6 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS PROVIDED (USED) BY OPERATING ACTIVITIES FROM CONTINUING OPERATIONS
Net income (loss)		$ 28	$ 69
Income from discontinued operations (net of income taxes)		(54)	(59)
Adjustments to reconcile income from continuing operations to cash flows from operating activities
Depreciation and amortization		163	142
Original issue discount and debt issuance costs amortization		4	3
Deferred income taxes		2	4
Distributions from affiliates			1
Stock based compensation expense		13	13
Loss (income) from restricted investments		(2)	(8)
Excess tax benefit on stock based compensation		2	2
Net (income) loss on divestitures		3	1
Impairments		5
Pension contributions		(3)	(7)
Gain on pension and other postretirement plan remeasurements		(18)
Change in operating assets and liabilities	[1]	(137)	(164)
Total cash flows provided (used) by operating activities from continuing operations		6	(3)
CASH FLOWS PROVIDED (USED) BY INVESTING ACTIVITIES FROM CONTINUING OPERATIONS
Additions to property, plant and equipment		(70)	(52)
Proceeds from disposal of property, plant and equipment		4	1
Purchase of operations		(1)	(11)
Proceeds from sales of operations			1
Life insurance payments			(37)
Net purchase of funds restricted for specific transactions		(2)	(8)
Reimbursement from restricted investments		20	17
Proceeds from sales of securities		156	17
Purchase of securities		(156)	(17)
Proceeds from the settlement of derivative instruments		2
Payments for the settlement of derivative instruments		(2)	(3)
Total cash flows used by investing activities from continuing operations		(49)	(92)
CASH FLOWS PROVIDED (USED) BY FINANCING ACTIVITIES FROM CONTINUING OPERATIONS
Repayment of long-term debt		(8)	(3)
Proceeds from (repayment of) short-term debt		11	(181)
Cash dividends paid		(31)	(28)
Stock based compensation employee withholding taxes paid in cash		(8)	(8)
Total cash flows used by financing activities from continuing operations		(36)	(220)
CASH PROVIDED (USED) BY CONTINUING OPERATIONS		(79)	(315)
Cash used by discontinued operations
Operating cash flows		(41)	(21)
Investing cash flows		(8)	(8)
Total cash used by discontinued operations		(49)	(29)
Effect of currency exchange rate changes on cash and cash equivalents		(2)	3
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		(130)	(341)
CASH AND CASH EQUIVALENTS - BEGINNING OF PERIOD		294	566
CASH AND CASH EQUIVALENTS - END OF PERIOD		$ 164	$ 225
[1]	Excludes changes resulting from operations acquired, sold or held for sale.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Significant Accounting Policies	ASHLAND GLOBAL HOLDINGS INC. AND CONSOLIDATED SUBSIDIARIES NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS NOTE A – SIGNIFICANT ACCOUNTING POLICIES Basis of presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and Securities and Exchange Commission (SEC) regulations. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. Additionally, certain prior period data, primarily related to discontinued operations, have been reclassified in the Consolidated Financial Statements and accompanying notes to conform to the current period presentation, as further described in this section. These statements omit certain information and footnote disclosures required for complete annual financial statements and, therefore, should be read in conjunction with Ashland Global Holdings Inc.’s (Ashland or the Company) Annual Report on Form 10-K for the fiscal year ended September 30, 2018. Results of operations for the period ended March 31, 2019 are not necessarily indicative of the expected results for the remaining quarters in the fiscal year. On November 15, 2018, Ashland announced that it had signed a definitive agreement to sell substantially all of the assets and liabilities of its Composites segment and Intermediates and Solvents facility in Marl, Germany (Marl facility). This expected divestiture represents a strategic shift in Ashland's business and, in accordance with U.S. GAAP, qualified as a discontinued operation. As a result, the operating results and cash flows related to Composites and the Marl facility have been reflected as discontinued operations in the Statements of Consolidated Comprehensive Income (Loss) and Statements of Condensed Consolidated Cash Flows. The assets and liabilities that are to be sold have met the requirements to be classified within the Condensed Consolidated Balance Sheets under a held for sale designation. See Notes B and C for additional information on this expected divestiture. As a result of classifying the Composites reporting segment as a discontinued operation, Ashland is now comprised of two reportable segments: Specialty Ingredients and Intermediates and Solvents. The financial information reported for Intermediates and Solvents excludes the activity from the Marl facility due to the expected divestiture. Use of estimates, risks and uncertainties The preparation of Ashland’s Condensed Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosures of contingent assets and liabilities. Significant items that are subject to such estimates and assumptions include, but are not limited to, long-lived assets (including goodwill and other intangible assets), income taxes and liabilities and receivables associated with asbestos litigation and environmental remediation. Although management bases its estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, actual results could differ significantly from the estimates under different assumptions or conditions. Ashland’s results are affected by domestic and international economic, political, legislative, regulatory and legal actions. Economic conditions, such as recessionary trends, inflation, interest and monetary exchange rates, government fiscal policies and changes in the prices of certain key raw materials, can have a significant effect on operations. While Ashland maintains reserves for anticipated liabilities and carries various levels of insurance, Ashland could be affected by civil, criminal, regulatory or administrative actions, claims or proceedings relating to asbestos, environmental remediation or other matters. New accounting pronouncements A description of new U.S. GAAP accounting standards issued or adopted during the current year is required in interim financial reporting. A detailed listing of new accounting standards relevant to Ashland is included in the Annual Report on Form 10-K for the fiscal year ended September 30, 2018. The following standards relevant to Ashland were either issued or adopted in the current period or will become effective in a subsequent period. Revenue recognition In May 2014, the FASB issued accounting guidance outlining a single comprehensive five step model for entities to use in accounting for revenue arising from contracts with customers (ASC 606 Revenue from Contracts with Customers). The new guidance and subsequent amendments to it superseded most current revenue recognition guidance, in an effort to converge the revenue recognition principles within U.S. GAAP. This new guidance required entities to disclose certain quantitative and qualitative information regarding the nature, amount, timing and uncertainty of qualifying revenue and cash flows arising from contracts with customers. Entities had the option of using a full retrospective or a modified retrospective approach to adopt the new guidance. This guidance became effective for Ashland on October 1, 2018. Ashland formed an implementation team that evaluated the impact of the new standard on the Condensed Consolidated Financial Statements and the adoption method options available as well as the overall impact the new guidance would have on the organization. The assessment process consisted of categorizing Ashland’s revenue streams and reviewing the current internal accounting policies and practices to determine potential differences that could result from applying the requirements of the new standard to revenue contracts. Additional discussions and meetings with each revenue stream team occurred to solicit input, identify potential impacts and appropriate changes to Ashland’s business processes, systems and controls to support the revenue recognition and disclosure requirements under the new standard. Ashland elected to adopt this standard using the modified retrospective approach and determined that the overall impact was not material to the Condensed Consolidated Financial Statements. As a result, no cumulative-effect adjustment was made to retained earnings in the Condensed Consolidated Balance Sheets. Leases In February 2016, the FASB issued new accounting guidance related to lease transactions. The main objective of this guidance is to increase transparency and comparability among organizations by requiring lessees to recognize assets and liabilities on the balance sheet for the right to use assets and obligations created by leases and to disclose key information about leasing arrangements. The presentation of the Statements of Consolidated Comprehensive Income (Loss) and the Statements of Condensed Consolidated Cash Flows is largely unchanged under this guidance. This guidance retains a distinction between finance leases and operating leases, and the classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in the current accounting literature. The guidance will become effective for Ashland on October 1, 2019 and it will have a significant effect on Ashland’s Condensed Consolidated Balance Sheet and disclosures. In July 2018, the FASB amended this guidance to give entities the option to apply the standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Ashland currently intends to utilize this transition method upon adopting the guidance. Ashland has formed an implementation team and is quantifying the impact that this guidance will have within its Condensed Consolidated Financial Statements. Other accounting pronouncements In January 2016, the FASB issued accounting guidance related to the recognition and measurement as well as the presentation and disclosures for certain financial instruments. Most notably, the guidance requires entities to measure equity investments at fair value and to recognize any changes in fair value in net income rather than accumulated other comprehensive income (AOCI). The guidance became effective for Ashland on October 1, 2018 and resulted in Ashland recording a cumulative-effect adjustment to reclassify net after-tax unrealized gains of $34 million on its equity securities from AOCI to retained earnings. In the current period, the adoption of this guidance resulted in a significant impact to net income as Ashland recognized investment gains of $27 million for the three months ended March 31, 2019 and investment losses of $3 million for the six months ended March 31, 2019 within the net interest and other expense (income) caption on the Statement of Consolidated Comprehensive Income (Loss). The impact of this new guidance could continue to have a material impact on Ashland’s Statements of Consolidated Comprehensive Income (Loss) in prospective periods depending on the fluctuations of unrealized gains and losses within the investment securities portfolio. For current and future periods, the changes in fair value of the equity securities will no longer be classified within other comprehensive income under the new guidance. For further information on Ashland’s equity securities, see Note E. In October 2016, the FASB issued new accounting guidance which requires entities to recognize the income tax effects of intercompany transfers of assets other than inventory when the transfer occurs. This guidance eliminates the exception under previous U.S. GAAP that the income tax effects of all intercompany transfers of assets other than inventory be deferred until the assets are sold to a third party or otherwise recovered through use. This guidance became effective for Ashland on October 1, 2018 and was applied using a modified retrospective approach. Consequently, Ashland recorded a cumulative-effect adjustment to reclassify less than $1 million from other current assets and deferred taxes to retained earnings.

Divestitures

Divestitures	6 Months Ended
	Mar. 31, 2019
Divestitures [Abstract]
Divestitures	NOTE B Composites and Marl facility On November 15, 2018, Ashland announced that it had signed a definitive agreement to sell its Composites segment and Intermediates and Solvents Marl facility to INEOS Enterprises in a transaction valued at $1.1 billion. Ashland will retain the remaining Intermediates and Solvents facility in Lima, Ohio primarily for its own internal business use. Ashland currently expects net proceeds from the sale to total approximately $1.0 billion and anticipates that the proceeds will be primarily used to reduce outstanding debt and other corporate purposes. The transaction is expected to close by late summer, contingent on certain customary regulatory approvals, standard closing conditions and completion of required employee information and consultation processes. Upon the closing of this transaction, Ashland currently expects to recognize a gain within the Statements of Consolidated Comprehensive Income (Loss). Since this transaction represents a strategic shift in Ashland’s business and had a major effect on Ashland’s operations and financial results, the operating results and cash flows related to Composites and the Marl facility have been reflected as discontinued operations in the Statements of Consolidated Comprehensive Income (Loss) and Statements of Condensed Consolidated Cash Flows. See Note C for the results of operations for Composites and the Marl facility for all periods presented. Certain indirect corporate costs included within the selling, general and administrative expense caption of the Statements of Consolidated Comprehensive Income (Loss) that were previously allocated to the Composites segment and Marl facility do not qualify for classification within discontinued operations and are now reported as selling, general and administrative expense within continuing operations on a consolidated basis and within the Unallocated and other segment. These costs were $12 million during both the three months ended March 31, 2019 and 2018, and $23 million Subsequent to the completion of the sale, Ashland expects to provide certain transition services to INEOS Enterprises for a fee. While the transition services are expected to vary in duration depending upon the type of service provided, Ashland expects to reduce costs as the transition services are completed. Other corporate assets Ashland is currently in the process of pursuing options to divest several corporate assets, primarily related to land and buildings, that are expected to close within the next 12 months. The net property, plant and equipment value related to these sites was $6 million at March 31, 2019 and $9 million at September 30, 2018. During the three months ended March 31, 2019, a $5 million impairment charge was recorded within the selling, general and administrative expense caption of the Statement of Consolidated Comprehensive Income (Loss) for one of these corporate assets. Held for sale classification The assets and liabilities of Composites and the Marl facility along with other corporate asset divestitures for current and prior periods have been reflected as assets and liabilities held for sale. As a result, in accordance with U.S. GAAP standards, depreciation and amortization are no longer being recorded within the Statements of Consolidated Comprehensive Income (Loss) and the Condensed Consolidated Balance Sheets. These assets and liabilities are comprised of the following components: March 31 September 30 (In millions) 2019 2018 Accounts receivable, net (a) $ 173 $ 159 Inventories 67 67 Net property, plant and equipment 254 — Goodwill 143 — Intangibles 38 — Deferred income taxes 7 — Other assets 57 14 Current assets held for sale $ 739 $ 240 Net property, plant and equipment $ — $ 254 Goodwill — 144 Intangibles — 40 Deferred income taxes — 7 Other assets — 32 Noncurrent assets held for sale $ — $ 477 Trade and other payables $ 112 $ 152 Employee benefit obligations 22 — Accrued expenses and other liabilities 10 11 Other liabilities 3 — Current liabilities held for sale $ 147 $ 163 Employee benefit obligations — 23 Other liabilities — 3 Noncurrent liabilities held for sale $ — $ 26 (a) Accounts receivable included an allowance for doubtful accounts of $3 million at both March 31, 2019 and September 30, 2018.

Discontinued Operations

Discontinued Operations	6 Months Ended
	Mar. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
Discontinued Operations	In previous periods, Ashland has divested certain businesses that have qualified as discontinued operations. The operating results from these divested businesses and subsequent adjustments related to ongoing assessments of certain retained liabilities and tax items have been recorded within the discontinued operations caption in the Statements of Consolidated Comprehensive Income (Loss) for all periods presented and are discussed further within this note. As previously described in Note B, Ashland completed the distribution of its remaining shares of common stock of Valvoline Inc. on May 12, 2017. Ashland determined that the Valvoline separation qualified as a discontinued operation, in accordance with U.S. GAAP, since it represented a strategic shift for Ashland and had a major effect on Ashland's operations and financial results. Ashland has made subsequent tax adjustments to the discontinued operations caption related to this transaction. Components of amounts reflected in the Statements of Consolidated Comprehensive Income (Loss) related to discontinued operations are presented in the following table for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Income (loss) from discontinued operations (net of tax) Composites/Marl facility $ 28 $ 24 $ 53 $ 49 Valvoline 1 4 1 7 Asbestos-related litigation — 3 — 3 Water Technologies 2 — 1 — Distribution — — (1 ) — $ 31 $ 31 $ 54 $ 59 The following table presents a reconciliation of the captions within Ashland's Statements of Consolidated Comprehensive Income (Loss) for the income (loss) from discontinued operations attributable to Composites and the Marl facility for the three and six months ended March 31, 2019 and 2018. Interest expense was allocated to discontinued operations based on Ashland’s mandatory debt prepayments upon the disposition of Composites and the Marl facility. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Income (loss) from discontinued operations attributable to Composites/Marl facility Sales $ 284 $ 302 $ 559 $ 563 Cost of sales (217 ) (250 ) (434 ) (461 ) Selling, general and administrative expense (19 ) (17 ) (41 ) (34 ) Research and development expense (3 ) (3 ) (6 ) (5 ) Equity and other income (expense) — (1 ) 3 2 Pretax operating income of discontinued operations 45 31 81 65 Net interest and other (expense) income (6 ) (5 ) (12 ) (9 ) Pretax income of discontinued operations 39 26 69 56 Income tax expense (11 ) (2 ) (16 ) (7 ) Income from discontinued operations $ 28 $ 24 $ 53 $ 49

Restructuring Activities

Restructuring Activities	6 Months Ended
	Mar. 31, 2019
Restructuring And Related Activities [Abstract]
Restructuring Activities	NOTE D – RESTRUCTURING ACTIVITIES Ashland periodically implements company-wide restructuring programs related to acquisitions, divestitures and other cost reduction programs in order to enhance profitability through streamlined operations and an improved overall cost structure. Severance costs During fiscal 2018, Ashland announced and initiated a company-wide cost reduction program as a result of ongoing strategic asset plans and activities. As part of this restructuring program, Ashland announced a voluntary severance offer (VSO) to certain qualifying employees that was formally approved during 2018. Additionally, during fiscal 2018, an involuntary program for employees was also initiated as part of the restructuring program. The VSO and involuntary programs resulted in a severance charge of $36 million during the September 2018 quarter of fiscal 2018. During the three and six months ended March 31, 2019, these programs resulted in additional severance expense of zero and $4 million, respectively, which was primarily recorded within the selling, general and administrative expense caption of the Statement of Consolidated Comprehensive Income (Loss). As of March 31, 2019, the severance reserve for the company-wide restructuring program was $22 million. Facility costs Ashland incurred $1 million and $8 million of lease abandonment charges during the three and six months ended March 31, 2019, respectively, due to the exit from certain office facilities in conjunction with the company-wide cost reduction program. No charges were incurred for the three or six months ended March 31, 2018. The costs related to these reserves were recorded within the selling, general and administrative expense caption of the Statements of Consolidated Comprehensive Income (Loss) and are paid over the remaining lease terms. As of March 31, 2019, the reserve for facility costs was $10 million. The following table details at March 31, 2019, the amount of restructuring reserves related to the programs discussed above, and the related activity in these reserves during the six months ended March 31, 2019. The severance and facility cost reserves were primarily recorded within accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet as of March 31, 2019. (In millions) Severance costs Facility costs Total Balance as of September 30, 2018 36 7 43 Restructuring reserve 4 8 12 Utilization (cash paid) (18 ) (5 ) (23 ) Balance as of March 31, 2019 $ 22 $ 10 32 Plant restructuring During the three and six months ended March 31, 2019, Specialty Ingredients committed to a cost reduction plan within an existing manufacturing facility. As a result, Ashland incurred restructuring charges of $20 million and $47 million for the three and six months ended March 31, 2019, respectively. These charges were recorded primarily within the cost of sales caption of the Statements of Consolidated Comprehensive Income (Loss) consisting of $38 million of accelerated depreciation and amortization, $5 million of severance and $4 million of plant closure costs during the six months ended March 31, 2019. As of March 31, 2019, there was a restructuring reserve of $5 million related to the $5 million of severance costs and $4 million related to the $4 million of plant closure costs. The restructuring plan is expected to be completed during fiscal 2019.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	As required by U.S. GAAP, Ashland uses applicable guidance for defining fair value, the initial recording and periodic remeasurement of certain assets and liabilities measured at fair value and related disclosures for instruments measured at fair value. Fair value accounting guidance establishes a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). An instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the instrument’s fair value measurement. The three levels within the fair value hierarchy are described as follows. Level 1 – Observable inputs such as unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3 – Unobservable inputs for the asset or liability for which there is little, if any, market activity at the measurement date. Unobservable inputs reflect Ashland’s own assumptions about what market participants would use to price the asset or liability. The inputs are developed based on the best information available in the circumstances, which might include Ashland’s own financial data such as internally developed pricing models, discounted cash flow methodologies, as well as instruments for which the fair value determination requires significant management judgment. For assets that are measured using quoted prices in active markets (Level 1), the total fair value is the published market price per unit multiplied by the number of units held without consideration of transaction costs. Assets and liabilities that are measured using significant other observable inputs (Level 2) are primarily valued by reference to quoted prices of similar assets or liabilities in active markets, adjusted for any terms specific to that asset or liability. For all other assets and liabilities for which unobservable inputs are used (Level 3), fair value is derived using fair value models, such as a discounted cash flow model or other standard pricing models that Ashland deems reasonable. The following table summarizes financial instruments subject to recurring fair value measurements as of March 31, 2019. Carrying Total fair Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs (In millions) value value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 164 $ 164 $ 164 $ — $ — Restricted investments (a) 326 326 326 — — Deferred compensation investments (b) 166 166 — 166 — Investment of captive insurance company 4 4 4 — — Foreign currency derivatives 3 3 — 3 — Total assets at fair value $ 663 $ 663 $ 494 $ 169 $ — Liabilities Foreign currency derivatives $ 3 $ 3 $ — $ 3 $ — (a) Included in restricted investments is $30 million classified in the other current assets caption on the Condensed Consolidated Balance Sheets. (b) Included in other noncurrent assets in the Condensed Consolidated Balance Sheets. The following table summarizes financial asset instruments subject to recurring fair value measurements as of September 30, 2018. Carrying Total fair Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs (In millions) value value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 294 $ 294 $ 294 $ — $ — Restricted investments (a) 342 342 342 — — Deferred compensation investments (b) 165 165 — 165 — Investment of captive insurance company 3 3 3 — — Foreign currency derivatives 11 11 — 11 — Total assets at fair value $ 815 $ 815 $ 639 $ 176 $ — Liabilities Foreign currency derivatives $ 3 $ 3 $ — $ 3 $ — (a) Included in restricted investments is $30 million classified in the other current assets caption on the Condensed Consolidated Balance Sheets. (b) Included in other noncurrent assets in the Condensed Consolidated Balance Sheets. Restricted investments Investment income and realized gains and losses on these company-restricted investments are reported within the net interest and other financing expense caption on the Statements of Consolidated Comprehensive Income (Loss). In prior periods, the unrealized gains and losses on the equity securities were reported within the stockholders' equity section of the Condensed Consolidated Balance Sheets as a component of AOCI, net of the related deferred income taxes. Due to the accounting guidance adopted in the current year, as discussed in Note A, the unrealized gains and losses are now recognized in net income and are recorded within the net interest and other expense (income) caption in the Statements of Consolidated Comprehensive Income (Loss). The following table provides a summary of the activity within the investment portfolio as of March 31, 2019 and September 30, 2018: (In millions) March 31 2019 September 30 2018 Original cost $ 335 $ 335 Accumulated adjustments, net (47 ) (38 ) Adjusted cost, beginning of year (a) 288 297 Investment income (b) 5 8 Net unrealized gain (c) 25 54 Realized gains (c) 26 6 Settlement funds 2 10 Disbursements (20 ) (33 ) Fair value $ 326 $ 342 (a) The accumulated adjustments include investment income, realized gains, disbursements and settlements recorded in previous periods. (b) Investment income for the demand deposit includes interest income as well as dividend income transferred from the equity and corporate bond mutual funds. (c) Presented under the original cost method. The following table presents gross unrealized gains and losses for the restricted investment securities as of March 31, 2019 and September 30, 2018: Gross Gross (In millions) Adjusted Cost Unrealized Gain Unrealized Loss Fair Value As of March 31, 2019 Demand deposit $ 164 $ — $ — $ 164 Equity mutual fund 71 25 — 96 Corporate bond mutual fund 66 — — 66 Fair value $ 301 $ 25 $ — $ 326 As of September 30, 2018 Demand deposit $ 20 $ — $ — $ 20 Equity mutual fund 148 59 — 207 Corporate bond mutual fund 120 — (5 ) 115 Fair value $ 288 $ 59 $ (5 ) $ 342 The unrealized gains and losses of $54 million, net of the related deferred income taxes of $20 million, as of September 30, 2018, were reclassified from AOCI to retained earnings within the Condensed Consolidated Balance Sheets due to the new accounting guidance adopted in the first quarter of fiscal year 2019. The following table presents the investment income, net unrealized gains and losses, realized gains and disbursements related to the investments within the portfolio for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Investment income $ 2 $ 2 $ 5 $ 4 Net unrealized gains (losses) (a) 27 (8 ) (3 ) 2 Realized gains (b) — 3 — 4 Disbursements (12 ) (12 ) (20 ) (17 ) (a) Ashland determined that all unrealized gains and losses were related to equity securities with readily determinable fair values. Due to the new accounting guidance adopted in the first quarter of fiscal year 2019, the net unrealized losses during the three and six months ended March 31, 2019 were recorded within the net interest and other expense (income) caption in the Statements of Consolidated Comprehensive Income (Loss). In 2018 these net unrealized gains (losses) were in AOCI. (b) Relates only to the three and six months ended March 31, 2018 prior to the adoption of the new accounting guidance for equity securities. Deferred compensation investments Deferred compensation investments consist of Level 2 measurements within the fair value hierarchy which are comprised primarily of a guaranteed interest fund, a common stock index fund and an intermediate investment grade bond fund. Gains and losses related to deferred compensation investments are immediately recognized within the selling, general and administrative expense caption on the Statements of Consolidated Comprehensive Income (Loss). These investments generated gains of $5 million and zero and $1 million and $4 million during the three and six months ended March 31, 2019 and 2018, respectively. Foreign currency derivatives Ashland conducts business in a variety of foreign currencies. Accordingly, Ashland regularly uses foreign currency derivative instruments to manage exposure on certain transactions denominated in foreign currencies to curtail potential earnings volatility effects on certain assets and liabilities, including short-term inter-company loans, denominated in currencies other than Ashland’s functional currency of an entity. These derivative contracts generally require exchange of one foreign currency for another at a fixed rate at a future date and generally have maturities of less than twelve months. All contracts are valued at fair value with net changes in fair value recorded within the selling, general and administrative expense caption. The impacts of these contracts were largely offset by gains and losses resulting from the impact of changes in exchange rates on transactions denominated in non-functional currencies. The following table summarizes the net gains and losses recognized during the three and six months ended March 31, 2019 and 2018 within the Statements of Consolidated Comprehensive Income (Loss). Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Foreign currency derivative gains (losses) $ 3 $ (16 ) $ 4 $ (27 ) The following table summarizes the fair values of the outstanding foreign currency derivatives as of March 31, 2019 and September 30, 2018 included in accounts receivable and accrued expenses and other liabilities of the Condensed Consolidated Balance Sheets. March 31 September 30 (In millions) 2019 2018 Foreign currency derivative assets $ 3 $ 11 Notional contract values 319 1,209 Foreign currency derivative liabilities $ 3 $ 3 Notional contract values 378 755 Other financial instruments At March 31, 2019 and September 30, 2018, Ashland's long-term debt (including the current portion and excluding debt issuance cost discounts) had a carrying value of $2,300

Inventories

Inventories	6 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories	NOTE F – INVENTORIES Inventories are carried at the lower of cost or net realizable value. Inventories are primarily stated at cost using the weighted-average cost method. In addition, certain inventories are valued at cost using the last-in, first-out (LIFO) method. The following table summarizes Ashland’s inventories as of the reported Condensed Consolidated Balance Sheet dates. (In millions) March 31, 2019 September 30, 2018 Finished products $ 378 $ 381 Raw materials, supplies and work in process 221 215 $ 599 $ 596

Goodwill and Other Intangibles

Goodwill and Other Intangibles	6 Months Ended
	Mar. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	NOTE G – GOODWILL AND OTHER INTANGIBLES Goodwill Ashland reviews goodwill and indefinite-lived intangible assets for impairment annually or when events and circumstances indicate an impairment may have occurred. This annual assessment is performed as of July 1 and consists of Ashland determining each reporting unit’s current fair value compared to its current carrying value. For its July 1, 2018 assessment, Ashland determined that its reporting units for the allocation of goodwill were its three reportable segments: Specialty Ingredients, Composites and Intermediates and Solvents. At that time, Ashland determined no additional impairment existed. Due to the expected divestiture of the Composites reporting unit, Ashland has two remaining reporting units as of March 31, 2019: Specialty Ingredients and Intermediates and Solvents. See Note B for more information on the expected divestiture. The following is a progression of goodwill by reportable segment for the six months ended March 31, 2019. Specialty Intermediates (In millions) Ingredients and Solvents (a) Total Balance at September 30, 2018 $ 2,304 $ — $ 2,304 Acquisitions — — — Currency translation (25 ) — (25 ) Balance at March 31, 2019 $ 2,279 $ — $ 2,279 (a) As of March 31, 2019 and September 30, 2018, there was accumulated impairment of $90 million related to the Intermediates and Solvents reportable segment. Intangibles Intangible assets principally consist of trademarks and trade names, intellectual property and customer and supplier relationships. Intangible assets classified as finite are amortized on a straight-line basis over their estimated useful lives. The cost of trademarks and trade names is amortized principally over 3 to 25 years, intellectual property over 5 to 25 years, and customer and supplier relationships over 3 to 24 years. Ashland annually reviews indefinite-lived intangible assets for possible impairment or whenever events or changes in circumstances indicate that carrying amounts may not be recoverable. Intangible assets were comprised of the following as of March 31, 2019 and September 30, 2018. March 31, 2019 Gross Net carrying Accumulated carrying (In millions) amount amortization amount Definite-lived intangibles Trademarks and trade names $ 66 $ (27 ) $ 39 Intellectual property 715 (370 ) 345 Customer and supplier relationships 750 (277 ) 473 Total definite-lived intangibles 1,531 (674 ) 857 Indefinite-lived intangibles Trademarks and trade names 278 — 278 Total intangible assets $ 1,809 $ (674 ) $ 1,135 September 30, 2018 Gross Net carrying Accumulated carrying (In millions) amount amortization amount Definite-lived intangibles Trademarks and trade names $ 66 $ (25 ) $ 41 Intellectual property 721 (350 ) 371 Customer and supplier relationships 759 (264 ) 495 Total definite-lived intangibles 1,546 (639 ) 907 Indefinite-lived intangibles Trademarks and trade names 278 — 278 Total intangible assets $ 1,824 $ (639 ) $ 1,185 Amortization expense recognized on intangible assets was $21 million and $23 million for the three months ended March 31, 2019 and 2018, respectively, and $43 million and $46 million for the six months ended March 31 2019 and 2018, respectively, and is included in the selling, general and administrative expense caption of the Statements of Consolidated Comprehensive Income (Loss). Estimated amortization expense for future periods is $86 million in 2019 (includes six months actual and six months estimated), $86 million in 2020, $85 million in 2021, $85 million in 2022 and $84 million in 2023. The amortization expense for future periods is an estimate. Actual amounts may change from such estimated amounts due to fluctuations in foreign currency exchange rates, additional intangible asset acquisitions and divestitures, potential impairment, accelerated amortization, or other events.

Debt

Debt	6 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	NOTE H – DEBT The following table summarizes Ashland’s current and long-term debt as of the dates reported in the Condensed Consolidated Balance Sheets. (In millions) March 31, 2019 September 30, 2018 4.750% notes, due 2022 $ 1,083 $ 1,083 Term Loan B, due 2024 590 593 6.875% notes, due 2043 376 376 Term Loan A, due 2022 195 195 Accounts receivable securitizations 207 195 6.50% junior subordinated notes, due 2029 53 52 Revolving credit facility 25 25 Medium-term notes, due 2019, interest of 9.4% — 5 Other (a) 7 5 Total debt 2,536 2,529 Short-term debt (includes current portion of long-term debt) (261 ) (254 ) Long-term debt (less current portion) $ 2,275 $ 2,275 (a) Includes $19 million and $21 million of debt issuance cost discounts as of March 31, 2019 and September 30, 2018, respectively, in addition to a European short-term loan facility with an outstanding balance of $23 million at both March 31, 2019 and September 30, 2018. The scheduled aggregate maturities of long-term debt by year (including the current portion and excluding debt issuance costs) are as follows: $3 million remaining in 2019, $6 million in 2020, $14 million in 2021, $1,279 million in 2022 and $6 million in 2023. Available borrowing capacity The borrowing capacity remaining under the 2017 Covenants related to current Ashland debt agreements Ashland's debt contains usual and customary representations, warranties and affirmative and negative covenants, including financial covenants for leverage and interest coverage ratios, limitations on liens, additional subsidiary indebtedness, restrictions on subsidiary distributions, investments, mergers, sale of assets and restricted payments and other customary limitations. As of March 31, 2019, Ashland is in compliance with all debt agreement covenant restrictions. The maximum consolidated net leverage ratio permitted under Ashland's most recent credit agreement (the 2017 Credit Agreement) is 4.5. At March 31, 2019, Ashland’s calculation of the consolidated net leverage ratio was 3.5. The minimum required consolidated interest coverage ratio under the 2017 Credit Agreement during its entire duration is 3.0. At March 31, 2019, Ashland’s calculation of the interest coverage ratio was 5.6.

Income Taxes

Income Taxes	6 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Tax Law Changes The Tax Cuts and Jobs Act (Tax Act) was enacted on December 22, 2017. The Tax Act reduced the U.S. federal corporate tax rate from 35% to 21%, required companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and created new taxes on certain foreign sourced earnings. Through September 30, 2018 we recorded provisional amounts for certain enactment date effects of the Tax Act by applying the guidance in SAB 118 because we had not yet completed our enactment date accounting for these effects. During 2019, Ashland completed its internal accounting assessment for the tax effects of enactment of the Tax Act and recorded adjustments to provisional amounts previously recorded. Ashland’s final assessment resulted in net unfavorable tax adjustments of $24 million during the three months ended December 31, 2018 primarily related to the one-time transition tax assessed on foreign cash and unremitted earnings. There could be additional guidance issued subsequent to December 31, 2018 that could impact our interpretation of the Tax Act and such changes could affect the amounts recorded. The impact, if any, of further transitional tax guidance that may be issued by the U.S. Treasury would be reflected in the Company’s provision for income tax in the period such guidance is effective. Deferred tax assets and liabilities Ashland remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is 21%. Ashland finalized its assessment of the provisional amount previously recorded for the remeasurement of the deferred tax balance which resulted in an unfavorable tax adjustment of $2 million during the three months ended December 31, 2018. Foreign tax effects The one-time transition tax is based on Ashland's total post-1986 earnings and profits of foreign subsidiaries that were previously deferred from U.S. income taxes. Ashland finalized its assessment of the provisional amount previously recorded for this one-time transition tax liability which resulted in an unfavorable tax adjustment of $22 million during the three months ended December 31, 2018. After this final adjustment, the obligation for the one-time transition tax was $51 million as of December 31, 2018. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax, or any additional outside basis difference inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations. Ashland determined that the amount of unrecognized deferred tax liability related to any remaining undistributed foreign earnings not subject to the transition tax and additional outside basis difference in these entities (i.e., basis difference in excess of that subject to the one-time transition tax) is not practicable at this time. Global Intangible Low-Taxed Income Regarding new Global Intangible Low-Taxed Income (GILTI) tax rules, Ashland made an election to treat taxes due on future GILTI exclusions as a current period expense when incurred. Current fiscal year Ashland’s effective tax rate in any interim period is subject to adjustments related to discrete items and the mix of domestic and foreign operating results. The overall effective tax rate was 2% for the three months ended March 31, 2019 and a negative 2500% for the six months ended March 31, 2019. The current quarter tax rate was primarily impacted by income mix, certain nondeductible restructuring costs, as well as $11 million in favorable tax discrete items including nontaxable earnings in deferred compensation related investments and other items. The current six month period was primarily impacted by the items referenced in the three-month period, as well as a net $30 million from unfavorable tax discrete items including the final assessment of the Tax Act and other items. Prior fiscal year The overall effective tax rate was negative 5% for the three months ended March 31, 2018 and 44% for the six months ended March 31, 2018. The quarter rate was primarily impacted by income mix and net favorable tax discrete adjustments of $5 million related to a tax rate change in a foreign country and other items. The six-month period was primarily impacted by the items referenced in the quarter, as well as a net $16 million from unfavorable tax discrete items including the assessment of the Tax Act and other items. Unrecognized tax benefits Changes in unrecognized tax benefits are summarized as follows for the six months ended March 31, 2019. (In millions) Balance at October 1, 2018 $ 164 Decreases related to positions taken on items from prior years (3 ) Increases related to positions taken in the current year 3 Lapse of statute of limitations (2 ) Balance at March 31, 2019 $ 162 From a combination of statute expirations and audit settlements in the next twelve months, Ashland expects a decrease in the amount accrued for uncertain tax positions of between $2 million and $4 million for continuing operations. It is reasonably possible that there could be other material changes to the amount of uncertain tax positions due to activities of the taxing authorities, settlement of audit issues or the reassessment of existing uncertain tax positions; however, Ashland is not able to estimate the impact of these items at this time.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Mar. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	Plan contributions For the six months ended March 31, 2019, Ashland contributed $3 million to its non-U.S. pension plans and zero to its U.S. pension plans. Ashland expects to make additional contributions of approximately $3 million to its non-U.S. plans during the remainder of 2019. Plan remeasurement Ashland settled a non-U.S. pension plan during the first quarter of fiscal 2019, which required the plan to be remeasured. This remeasurement resulted in a curtailment gain of $18 million. Components of net periodic benefit costs (income) The following table details the components of pension and other postretirement benefit costs for continuing operations. Pension benefits Other postretirement benefits (In millions) 2019 2018 2019 2018 Three months ended March 31 Service cost $ 1 $ 2 $ — $ — Interest cost 2 2 1 — Expected return on plan assets (2 ) (3 ) — — Curtailment — — — — Actuarial (gain) loss — — — — Total net periodic benefit costs $ 1 $ 1 $ 1 $ — Six months ended March 31 Service cost $ 3 $ 4 $ — $ 1 Interest cost 5 5 1 — Expected return on plan assets (5 ) (6 ) — — Curtailment (18 ) — — — Actuarial gain — — — — Total net periodic benefit costs (income) $ (15 ) $ 3 $ 1 $ 1 For segment reporting purposes, service cost is proportionately allocated to each segment, excluding the Unallocated and other segment, and is recorded within the selling, general and administrative expense and cost of sales captions on the Statements of Consolidated Comprehensive Loss (Income). All other components are recorded within the other net periodic benefit income caption on the Statements of Consolidated Comprehensive Loss (Income).

Litigation, Claims and Continge

Litigation, Claims and Contingencies	6 Months Ended
	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Litigation, Claims and Contingencies	Asbestos litigation Ashland and Hercules have liabilities from claims alleging personal injury caused by exposure to asbestos. To assist in developing and annually updating independent reserve estimates for future asbestos claims and related costs given various assumptions, Ashland retained Nathan Associates Inc. (Nathan). The methodology used by Nathan to project future asbestos costs is based largely on recent experience, including claim-filing and settlement rates, disease mix, enacted legislation, open claims and litigation defense. The claim experience of Ashland and Hercules are separately compared to the results of previously conducted third party epidemiological studies estimating the number of people likely to develop asbestos-related diseases. Those studies were undertaken in connection with national analyses of the population expected to have been exposed to asbestos. Using that information, Nathan estimates a range of the number of future claims that may be filed, as well as the related costs that may be incurred in resolving those claims. Changes in asbestos-related liabilities and receivables are recorded on an after-tax basis within the discontinued operations caption in the Statements of Consolidated Comprehensive Income (Loss). Ashland asbestos-related litigation The claims alleging personal injury caused by exposure to asbestos asserted against Ashland result primarily from indemnification obligations undertaken in 1990 in connection with the sale of Riley Stoker Corporation (Riley). The amount and timing of settlements and number of open claims can fluctuate from period to period. A summary of Ashland asbestos claims activity, excluding Hercules claims, follows. Six months ended March 31 Years ended September 30 (In thousands) 2019 2018 2018 2017 2016 Open claims - beginning of year 53 54 54 57 60 New claims filed 1 1 2 2 2 Claims settled — — (1 ) (1 ) — Claims dismissed (1 ) (2 ) (2 ) (4 ) (5 ) Open claims - end of period 53 53 53 54 57 Ashland asbestos-related liability From the range of estimates, Ashland records the amount it believes to be the best estimate of future payments for litigation defense and claim settlement costs, which generally approximates the mid-point of the estimated range of exposure from model results. Ashland reviews this estimate and related assumptions quarterly and annually updates the results of a non-inflated, non-discounted approximate 50-year model developed with the assistance of Nathan. During the most recent annual update of this estimate completed during the June 2018 quarter, it was determined that the liability for Ashland asbestos-related claims should be decreased by $8 million. Total reserves for asbestos claims were $366 million at March 31, 2019 compared to $380 million at September 30, 2018. A progression of activity in the asbestos reserve is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Asbestos reserve - beginning of year $ 380 $ 419 $ 419 $ 415 $ 409 Reserve adjustment — — (8 ) 36 37 Amounts paid (14 ) (17 ) (31 ) (32 ) (31 ) Asbestos reserve - end of period (a) $ 366 $ 402 $ 380 $ 419 $ 415 (a) Includes $31 million and $30 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2019 and September 30, 2018, respectively. Ashland asbestos-related receivables Ashland has insurance coverage for certain litigation defense and claim settlement costs incurred in connection with its asbestos claims, and coverage-in-place agreements exist with the insurance companies that provide substantially all of the coverage that will be accessed. For the Ashland asbestos-related obligations, Ashland has estimated the value of probable insurance recoveries associated with its asbestos reserve based on management’s interpretations and estimates surrounding the available or applicable insurance coverage, including an assumption that all solvent insurance carriers remain solvent. A substantial portion of the estimated receivables from insurance companies are expected to be due from domestic insurers. At March 31, 2019, Ashland’s receivable for recoveries of litigation defense and claim settlement costs from insurers amounted to $136 million (excluding the Hercules receivable for asbestos claims) compared to $140 million at September 30, 2018. During the June 2018 quarter, the annual update of the model used for purposes of valuing the asbestos reserve and its impact on valuation of future recoveries from insurers was completed. This model update resulted in a $5 million decrease in the receivable for probable insurance recoveries. A progression of activity in the Ashland insurance receivable is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Insurance receivable - beginning of year $ 140 $ 155 $ 155 $ 151 $ 150 Receivable adjustment — — (5 ) 15 16 Insurance settlement — — — (5 ) (4 ) Amounts collected (4 ) (6 ) (10 ) (6 ) (11 ) Insurance receivable - end of period (a) $ 136 $ 149 $ 140 $ 155 $ 151 (a) Includes $15 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018. Hercules asbestos-related litigation Hercules has liabilities from claims alleging personal injury caused by exposure to asbestos. Such claims typically arise from alleged exposure to asbestos fibers from resin encapsulated pipe and tank products which were sold by one of Hercules’ former subsidiaries to a limited industrial market. The amount and timing of settlements and number of open claims can fluctuate from period to period. A summary of Hercules’ asbestos claims activity follows. Six months ended March 31 Years ended September 30 (In thousands) 2019 2018 2018 2017 2016 Open claims - beginning of year 13 12 12 15 20 New claims filed — 1 2 1 1 Claims dismissed (1 ) (1 ) (1 ) (4 ) (6 ) Open claims - end of period 12 12 13 12 15 Hercules asbestos-related liability From the range of estimates, Ashland records the amount it believes to be the best estimate of future payments for litigation defense and claim settlement costs, which generally approximates the mid-point of the estimated range of exposure from model results. Ashland reviews this estimate and related assumptions quarterly and annually updates the results of a non-inflated, non-discounted approximate 50-year model developed with the assistance of Nathan. As a result of the most recent annual update of this estimate, completed during the June 2018 quarter, it was determined that the liability for Hercules asbestos-related claims should be decreased by $19 million. Total reserves for asbestos claims were $272 million at March 31, 2019 compared to $282 million at September 30, 2018. A progression of activity in the asbestos reserve is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Asbestos reserve - beginning of year $ 282 $ 323 $ 323 $ 321 $ 311 Reserve adjustments — — (19 ) 16 25 Amounts paid (10 ) (12 ) (22 ) (14 ) (15 ) Asbestos reserve - end of period (a) $ 272 $ 311 $ 282 $ 323 $ 321 (a) Included $20 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018. Hercules asbestos-related receivables For the Hercules asbestos-related obligations, certain reimbursement obligations pursuant to coverage-in-place agreements with insurance carriers exist. As a result, any increases in the asbestos reserve have been partially offset by probable insurance recoveries. Ashland has estimated the value of probable insurance recoveries associated with its asbestos reserve based on management’s interpretations and estimates surrounding the available or applicable insurance coverage, including an assumption that all solvent insurance carriers remain solvent. The estimated receivable consists exclusively of solvent domestic insurers. As of March 31, 2019, Ashland’s receivable for recoveries of litigation defense and claims costs from insurers with respect to Hercules amounted to $54 million. During the June 2018 quarter, the annual update of the model used for purposes of valuing the asbestos reserve and its impact on valuation of future recoveries from insurers was completed. This model update resulted in a decrease of $14 million in the receivable for probable insurance recoveries. A progression of activity in the Hercules insurance receivable is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Insurance receivable - beginning of year $ 54 $ 68 $ 68 $ 63 $ 56 Receivable adjustment — — (14 ) 5 7 Insurance receivable - end of period $ 54 $ 68 $ 54 $ 68 $ 63 Asbestos litigation cost projection Projecting future asbestos costs is subject to numerous variables that are extremely difficult to predict. In addition to the significant uncertainties surrounding the number of claims that might be received, other variables include the type and severity of the disease alleged by each claimant, the long latency period associated with asbestos exposure, mortality rates, dismissal rates, costs of medical treatment, the impact of bankruptcies of other companies that are co-defendants in claims, uncertainties surrounding the litigation process from jurisdiction to jurisdiction and from case to case, and the impact of potential changes in legislative or judicial standards. Furthermore, any predictions with respect to these variables are subject to even greater uncertainty as the projection period lengthens. Considering these inherent uncertainties, Ashland believes that the asbestos reserves for Ashland and Hercules represent the best estimate within a range of possible outcomes. As a part of the process to develop these estimates of future asbestos costs, a range of long-term cost models was developed. These models are based on national studies that predict the number of people likely to develop asbestos-related diseases and are heavily influenced by assumptions regarding long-term inflation rates for indemnity payments and legal defense costs, as well as other variables mentioned previously. Ashland has currently estimated in various models ranging from approximately 40 to 50 year periods that it is reasonably possible that total future litigation defense and claim settlement costs on an inflated and undiscounted basis could range as high as approximately $600 million for the Ashland asbestos-related litigation (current reserve of $366 million) and approximately $450 million for the Hercules asbestos-related litigation (current reserve of $272 million), depending on the combination of assumptions selected in the various models. If actual experience is worse than projected, relative to the number of claims filed, the severity of alleged disease associated with those claims or costs incurred to resolve those claims, or actuarial refinement or improvements to the assumptions used within these models are initiated, Ashland may need to further increase the estimates of the costs associated with asbestos claims and these increases could be material over time. Environmental remediation and asset retirement obligations Ashland is subject to various federal, state and local environmental laws and regulations that require environmental assessment or remediation efforts (collectively, environmental remediation) at multiple locations. At March 31, 2019, such locations included 81 waste treatment or disposal sites where Ashland has been identified as a potentially responsible party under Superfund or similar state laws, 116 current and former operating facilities and about 1,225 service station properties, of which 31 are being actively remediated. Ashland’s reserves for environmental remediation and related environmental litigation amounted to $179 million at March 31, 2019 compared to $187 million at September 30, 2018, of which $139 million at March 31, 2019 and $147 million at September 30, 2018 were classified in other noncurrent liabilities on the Condensed Consolidated Balance Sheets. The remaining reserves were classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets. The following table provides a reconciliation of the changes in the environmental remediation reserves during the six months ended March 31, 2019 and 2018. Six months ended March 31 (In millions) 2019 2018 Reserve - beginning of period $ 187 $ 163 Disbursements (15 ) (16 ) Revised obligation estimates and accretion 7 17 Reserve - end of period $ 179 $ 164 The total reserves for environmental remediation reflect Ashland’s estimates of the most likely costs that will be incurred over an extended period to remediate identified conditions for which the costs are reasonably estimable, without regard to any third-party recoveries. Engineering studies, probability techniques, historical experience and other factors are used to identify and evaluate remediation alternatives and their related costs in determining the estimated reserves for environmental remediation. Ashland continues to discount certain environmental sites and regularly adjusts its reserves as environmental remediation continues. Ashland has estimated the value of its probable insurance recoveries associated with its environmental reserve based on management’s interpretations and estimates surrounding the available or applicable insurance coverage. At March 31, 2019 and September 30, 2018, Ashland’s recorded receivable for these probable insurance recoveries was $12 million, Components of environmental remediation expense included within the selling, general and administrative expense caption of the Statements of Consolidated Comprehensive Income (Loss) are presented in the following table for the three months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Environmental expense $ 3 $ 4 $ 6 $ 16 Accretion 1 — 1 1 Legal expense 2 2 3 3 Total expense 6 6 10 20 Insurance receivable (a) — (1 ) (1 ) (1 ) Total expense, net of receivable activity (b) $ 6 $ 5 $ 9 $ 19 (a) Activity of $0 denotes value less than $1 million. (b) Net expense of $1 million and $2 million for the three and six months ended March 31, 2019, and $1 million for both the three and six months ended March 31, 2018, relates to divested businesses which qualified for treatment as discontinued operations for which certain environmental liabilities were retained by Ashland. These amounts are classified within the income from discontinued operations caption of the Statements of Consolidated Comprehensive Income (loss). Environmental remediation reserves are subject to numerous inherent uncertainties that affect Ashland’s ability to estimate its share of the costs. Such uncertainties involve the nature and extent of contamination at each site, the extent of required cleanup efforts under existing environmental regulations, widely varying costs of alternate cleanup methods, changes in environmental regulations, the potential effect of continuing improvements in remediation technology, and the number and financial strength of other potentially responsible parties at multiparty sites. Although it is not possible to predict with certainty the ultimate costs of environmental remediation, Ashland currently estimates that the upper end of the reasonably possible range of future costs for identified sites could be as high as approximately $421 million. The largest reserve for any site is 15% of the remediation reserve. Other legal proceedings and claims In addition to the matters described above, there are other various claims, lawsuits and administrative proceedings pending or threatened against Ashland and its current and former subsidiaries. Such actions are with respect to commercial matters, product liability, toxic tort liability, and other environmental matters, which seek remedies or damages, some of which are for substantial amounts. While Ashland cannot predict with certainty the outcome of such actions, it believes that adequate reserves have been recorded and losses already recognized with respect to such actions were immaterial as of March 31, 2019 and September 30, 2018. There is a reasonable possibility that a loss exceeding amounts already recognized may be incurred related to these actions; however, Ashland believes that such potential losses were immaterial as of March 31, 2019 and September 30, 2018.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	The following is the computation of basic and diluted earnings per share (EPS) from continuing operations attributable to Ashland. Stock appreciation rights (SARs), stock options and warrants available to purchase shares outstanding for each reporting period whose grant price was greater than the average market price of Ashland Common Stock for each applicable period were not included in the computation of income from continuing operations per diluted share because the effect of these instruments would be antidilutive. The total number of these shares outstanding was approximately 1.0 million and 0.7 million at March 31, 2019 and 2018, respectively. Earnings per share is reported under the treasury stock method. Three months ended Six months ended March 31 March 31 (In millions, except per share data) 2019 2018 2019 2018 Numerator Numerator for basic and diluted EPS - Income (loss) from continuing operations $ 45 $ 42 $ (26 ) $ 10 Denominator Denominator for basic EPS - Weighted- average common shares outstanding 63 63 63 63 Share based awards convertible to common shares (a) 1 1 — 1 Denominator for diluted EPS - Adjusted weighted- average shares and assumed conversions 64 64 63 64 EPS from continuing operations Basic $ 0.72 $ 0.66 $ (0.41 ) $ 0.15 Diluted 0.71 0.65 (0.41 ) 0.15 (a) As a result of the loss from continuing operations attributable to Ashland during the six months ended March 31, 2019, the effect of the share-based awards convertible to common shares would be antidilutive. In accordance with U.S. GAAP, these shares have been excluded from the diluted EPS calculation.

Equity Items

Equity Items	6 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Equity Items	NOTE M Stock repurchase programs During March 2018, Ashland’s Board of Directors approved a new $1 billion stock repurchase program, which replaced the 2015 stock repurchase program. Under the new program, Ashland’s common shares may be repurchased in open market transactions, privately negotiated transactions or pursuant to one or more accelerated stock repurchase programs or Rule 10b5-1 plans. Stockholder dividends In January 2019, the Board of Directors of Ashland announced a quarterly cash dividend of 25 cents per share or $16 million, to eligible stockholders at record, which was paid in the second quarter of fiscal 2019. Similarly dividends of 25 cents per share were paid in the first quarter of fiscal 2019 and the third and fourth quarters of fiscal 2018. These dividends represented an 11% increase over the previous quarterly cash dividend of 22.5 cents per share paid in the first and second quarters of fiscal 2018. Accumulated other comprehensive income (loss) Components of other comprehensive income (loss) recorded in the Statements of Consolidated Comprehensive Income (Loss) are presented below, before tax and net of tax effects. 2019 2018 (In millions) Before tax Tax (expense) benefit Net of tax Before tax Tax (expense) benefit Net of tax Three months ended March 31 Other comprehensive income (loss) Unrealized translation gain (loss) $ (9 ) $ — $ (9 ) $ 55 $ — $ 55 Pension and postretirement obligation adjustment: Adjustment of unrecognized prior service costs — — — — — — Net change in investment securities: Unrealized gains during periods (a) — — — (5 ) 1 (4 ) Reclassification adjustment for gains included in net income — — — (3 ) 1 (2 ) Total other comprehensive income (loss) $ (9 ) $ — $ (9 ) $ 47 $ 2 $ 49 Six months ended March 31 Other comprehensive income (loss) Unrealized translation gain (loss) $ (40 ) $ — $ (40 ) $ 58 $ — $ 58 Pension and postretirement obligation adjustment: Adjustment of unrecognized prior service costs (7 ) 1 (6 ) — — — Net change in investment securities: Unrealized gains during periods (a) — — — 6 (1 ) 5 Reclassification adjustment for gains included in net income — — — (4 ) 1 (3 ) Total other comprehensive income (loss) $ (47 ) $ 1 $ (46 ) $ 60 $ — $ 60 ( a ) Summary of stockholders’ equity A reconciliation of changes in stockholders’ equity are as follows: Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Common stock and paid in capital Balance, beginning of period $ 948 $ 932 $ 947 $ 932 Common shares issued under stock incentive and other plans (a) 5 4 6 4 Balance, end of period 953 936 953 936 Retained earnings Balance, beginning of period 2,719 2,678 2,750 2,696 Adoption of new accounting pronouncements (b) 1 — 34 — Net income (loss) 76 73 28 69 Regular dividends (16 ) (14 ) (32 ) (28 ) Balance, end of period 2,780 2,737 2,780 2,737 Accumulated other comprehensive income (loss) Balance, beginning of period (362 ) (211 ) (291 ) (222 ) Adoption of new accounting pronouncements (b) — — (34 ) — Unrealized translation gain (loss) (9 ) 55 (40 ) 58 Pension and postretirement obligation adjustment — — (6 ) — Net change in investment securities — (6 ) — 2 Balance, end of period (371 ) (162 ) (371 ) (162 ) Total stockholders' equity $ 3,362 $ 3,511 $ 3,362 $ 3,511 Cash dividends declared per common share $ 0.25 $ 0.225 $ 0.50 $ 0.45 (a) Common share issued were 93,738 and 154,421 for the three months ended March 31, 2019 and 2018 and 234,352 and 265,821 for the six months ended March 31, 2019 and 2018. (b) Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and tax effects of intercompany transfers during fiscal 2019. See Note A for more information.

Stock Incentive Plans

Stock Incentive Plans	6 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	Ashland has stock incentive plans under which key employees or directors are granted stock appreciation rights (SARs), performance awards or nonvested stock awards. Each program is typically a long-term incentive plan designed to link employee compensation with increased shareholder value or reward superior performance and encourage continued employment with Ashland. Ashland recognizes compensation expense for the grant date fair value of stock-based awards over the applicable vesting period. The components of Ashland’s pre-tax stock-based compensation expense included in continuing operations are as follows: Three months ended Six months ended March 31 March 31 (In millions) 2019 (a) 2018 (b) 2019 (a) 2018 (b) SARs $ 2 $ 2 $ 4 $ 3 Nonvested stock awards 6 5 10 11 Performance share awards 2 2 2 6 $ 10 $ 9 $ 16 $ 20 (a) Included $2 million and $3 million of expense related to cash-settled nonvested restricted stock awards during the three and six months ended March 31, 2019 and $2 million of expense related to cash-settled performance units during the three ended March 31, 2019. (b) Included $2 million and $4 million of expense related to cash-settled nonvested restricted stock awards and $1 million and $3 million of expense related to cash-settled performance units during the three and six months ended March 31, 2018, respectively. SARs SARs are granted to employees or directors at a price equal to the fair market value of the stock on the date of grant and typically become exercisable over periods of one to three years. Unexercised SARs generally lapse ten years after the date of grant. SARs granted for six months ended March 31, 2019 and 2018 were 300 thousand and 470 thousand, respectively. As of March 31, 2019, there was $10 million of total unrecognized compensation costs related to SARs. That cost is expected to be recognized over a weighted-average period of 2.1 years. Ashland estimates the fair value of SARs granted using the Black-Scholes option-pricing model. This model requires several assumptions which Ashland has developed and updates based on historical trends and current market . Nonvested stock awards Nonvested stock awards are granted to employees or directors at a price equal to the fair market value of the stock on the date of grant and generally vest over a one-to-five-year period. However, such shares or units are subject to forfeiture upon termination of service before the vesting period ends. Only nonvested stock awards granted in the form of shares entitle employees or directors to vote the shares. Dividends on nonvested stock awards granted are in the form of additional units or shares of nonvested stock awards, which are subject to vesting and forfeiture provisions. Stock-settled nonvested stock awards Nonvested stock awards granted in the form of shares or units were 13 thousand and 2 thousand for the three months ended March 31, 2019 and 2018, respectively, and 94 thousand and 144 thousand for the six months ended March 31, 2019 and 2018, respectively. As of March 31, 2019, there was $11 million of total unrecognized compensation costs related to these nonvested stock awards. That cost is expected to be recognized over a weighted-average period of 1.9 years. Cash-settled nonvested stock awards Certain nonvested stock awards are granted to employees and are settled in cash upon vesting. As of March 31, 2019, 200 thousand cash-settled nonvested stock awards were outstanding. The value of these cash-settled nonvested stock awards changes in connection with changes in the fair market value of the Ashland Common Stock. These awards generally vest over a period of three years. The expense recognized related to cash-settled nonvested stock awards was $2 million during the three months ended March 31, 2019 and 2018, and $3 million and $4 million during the six months ended March 31, 2019 and 2018, respectively. Executive performance incentive and retention program During 2016, certain executives were granted performance-based restricted shares of Ashland in order to provide an incentive to remain employed in the period after the full separation of Ashland and Valvoline. At March 31, 2019, there were 30 thousand shares outstanding in connection with these awards, which includes forfeitures and the cumulative value of forfeitable dividends. The expense recognition for these awards commenced upon completing the full separation of Valvoline which occurred on May 12, 2017 and resulted in $1 million and $1 million and $2 million and $3 million of expense for the three and six months ended March 31, 2019 and 2018, respectively. As of March 31, 2019, there was $1 million of total unrecognized compensation costs related to these awards. Performance awards Ashland sponsors a long-term incentive plan that awards performance shares/units to certain key employees that are primarily tied to Ashland’s overall financial performance relative to internal targets. Additionally, certain outstanding performance awards are tied to Ashland's overall financial performance relative to the financial performance of selected industry peer groups. Awards are granted annually, with each award covering a three-year vesting period. Awards settled in shares are recorded as a component of stockholders’ equity while awards settled in cash are recorded as a liability within the Condensed Consolidated Balance Sheets. The performance measure used to determine the actual number of performance shares/units issuable upon vesting is the financial performance of Ashland compared to award targets. The financial performance award metric is considered a performance condition under applicable U.S. GAAP. Additionally, the actual number of performance shares/units issuable upon vesting can be potentially increased or decreased based on a total shareholder return (TSR) performance modifier relative to peers of Ashland. For awards granted in fiscal 2017, each performance unit will be settled in cash based on the fair value of Ashland common stock. For awards granted in fiscal 2018 and 2019, each performance share/unit is convertible to one share of Ashland Common Stock. Nonvested performance shares/units do not entitle employees to vote the shares or to receive any dividends thereon. No performance shares/units were granted for the three months ended March 31, 2019 and 2018. Performance shares/units granted for the six months ended March 31, 2019 and 2018 were 78 thousand and 101 thousand, respectively. As of March 31, 2019, there was $13 million of total unrecognized compensation costs related to performance shares/units. That cost is expected to be recognized over a weighted-average period of 2.0 years.

Revenue

Revenue	6 Months Ended
	Mar. 31, 2019
Revenue From Contract With Customer [Abstract]
Revenue	NOTE O – REVENUE Effective October 1, 2018, Ashland adopted accounting guidance outlining a single comprehensive five step model for entities to use in accounting for revenue arising from contracts with customers (ASC 606 Revenue from Contracts with Customers). As a result of the adoption, there was no material impact to Ashland’s Condensed Consolidated Financial Statements. The additional disclosures that Ashland is required to disclose on an interim and annual basis are contained within this Note O. Revenue recognition Ashland’s revenue is measured as the amount of consideration it expects to receive in exchange for transferring goods or providing services and is recognized when performance obligations are satisfied under the terms of contracts with customers. Ashland generally utilizes standardized language for the terms of contracts within each purchase order, unless a separate agreement has been entered into with a customer that supersedes the standard language within the purchase order. A performance obligation is deemed to be satisfied by Ashland when control of the product or service is transferred to the customer. The transaction price of a contract, or the amount Ashland expects to receive upon satisfaction of all performance obligations, is determined by reference to the contract’s terms and includes adjustments, if applicable, for any variable consideration, such as volume discounts, rebates, refunds and rights to return. Where a contract contains more than one distinct performance obligation, the transaction price is allocated to each performance obligation based on the standalone selling price of each performance obligation, although these situations do not occur frequently and are generally not included within Ashland’s contracts. Any unsatisfied performance obligations were not material. Standalone selling prices are based on prices Ashland charges to customers, which in some cases are based on established market prices. Ashland generally collects the cash from its customers within 60 days of the product delivery date. Sales and other similar taxes collected from customers on behalf of third parties are excluded from the contract price. All of Ashland’s revenue is derived from contracts with customers, and nearly all contracts with customers contain one performance obligation for the transfer of goods where such performance obligation is satisfied at a point in time. Control of a product is deemed to be transferred to the customer generally upon shipment or delivery. Costs for shipping and handling activities, whether performed before or after the customer obtains control of the goods, are accounted for as fulfillment costs when not reimbursed. Costs incurred to obtain contracts with customers have historically not been significant and are expensed immediately as the period of performance is generally one year or less. Ashland records bad debt expense in specific situations when it is determined that the customer is unable to meet its financial obligation. Practical expedients Upon adoption, Ashland utilized the following applicable practical expedients, as permitted by ASC 606, Revenue from Contracts with Customers: • Sales and other similar taxes collected from customers on behalf of third parties are excluded from the contract price; • Costs for shipping and handling activities, whether performed before or after the customer obtains control of the goods, are accounted for as fulfillment costs when not reimbursed; and • Costs incurred to obtain contracts with customers are expensed immediately when the amortization period is one year or less. Trade receivables Trade receivables are defined as receivables arising from contracts with customers and are recorded within the accounts receivable caption within the Condensed Consolidated Balance Sheets. Ashland’s trade receivables were $491 million and $482 million as of March 31, 2019 and September 30, 2018, respectively. Disaggregation of revenue Ashland disaggregates its revenue from contracts with customers by segment, geographical region and product category, as Ashland believes these categories best depict how management reviews the financial performance of its operations for the three and six months ended March 31, 2018 and 2019. See the following tables for details: Sales by geography (In millions) Specialty Ingredients Intermediates and Solvents Geography 2019 2018 2019 2018 Three months ended March 31 North America $ 247 $ 258 $ 15 $ 13 Europe 220 222 6 6 Asia Pacific 115 111 7 6 Latin America & other 55 55 2 1 $ 637 $ 646 $ 30 $ 26 Six months ended March 31 North America $ 466 $ 481 $ 26 $ 27 Europe 390 389 11 13 Asia Pacific 231 218 13 14 Latin America & other 103 108 3 3 $ 1,190 $ 1,196 $ 53 $ 57 Sales by product category (In millions) 2019 2018 Three months ended March 31 Ashland Specialty Ingredients Cellulosics $ 224 $ 215 Poly-vinyl pyrrolidones 110 115 Adhesives 89 90 Actives 43 42 Vinyl ethers 31 38 Pharmachem 64 63 Other 76 83 $ 637 $ 646 Intermediates and Solvents Derivatives $ 25 $ 21 Butanediol 5 5 $ 30 $ 26 Total $ 667 $ 672 Sales by product category (In millions) 2019 2018 Six months ended March 31 Ashland Specialty Ingredients Cellulosics $ 413 $ 393 Poly-vinyl pyrrolidones 205 210 Adhesives 171 169 Actives 80 80 Vinyl ethers 55 66 Pharmachem 123 121 Other 143 157 $ 1,190 $ 1,196 Intermediates and Solvents Derivatives $ 45 $ 48 Butanediol 8 9 $ 53 $ 57 Total $ 1,243 $ 1,253

Reportable Segment Information

Reportable Segment Information	6 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Reportable Segment Information	Ashland determines its reportable segments based on how operations are managed internally for the products and services sold to customers, including how the results are reviewed by the chief operating decision maker, which includes determining resource allocation methodologies used for reportable segments. Operating income is the primary measure on the Statements of Consolidated Comprehensive Income (Loss) that is reviewed by the chief operating decision maker in assessing each reportable segment's financial performance. Ashland does not aggregate operating segments to arrive at these reportable segments. Change in Reportable Segments Ashland’s reportable segments were impacted in the current year due to the expected divestiture of the Composites reportable segment and Intermediates and Solvents Marl facility and reclassification to discontinued operations. As a result, Ashland's operations are managed by the chief operating decision maker within the following two reportable segments: Specialty Ingredients and Intermediates and Solvents. The financial information for Intermediates and Solvents excludes the activity from the Marl facility due to the expected divestiture and has therefore been restated in prior periods. Reportable segment business descriptions Specialty Ingredients offers industry-leading products, technologies and resources for solving formulation and product-performance challenges. Using natural, synthetic and semisynthetic polymers derived from cellulose ethers, vinyl pyrrolidones, acrylic polymers, polyester and polyurethane-based adhesives, and plant and seed extract, Specialty Ingredients offers comprehensive and innovative solutions for consumer and industrial applications. Key customers include pharmaceutical companies; makers of personal care products, food and beverages; makers of nutraceuticals and supplements; manufacturers of paint, coatings and construction materials; packaging and converting; and oilfield service companies. Intermediates and Solvents is a leading producer of 1,4 butanediol and related derivatives, including tetrahydrofuran and n-methylpyrrolidone. These products are used as chemical intermediates in the production of engineering polymers and polyurethanes, and as specialty process solvents in a wide array of applications including electronics, pharmaceuticals, water filtration membranes and more. Butanediol is also supplied to Ashland’s Specialty Ingredients business for use as a raw material. On November 15, 2018, Ashland announced that it had signed a definitive agreement to sell its Composites segment and Intermediates and Solvents Marl facility. As a result, the financial information for Intermediates and Solvents excludes the activity from the Marl facility due to the expected divestiture and has been restated in prior periods. Unallocated and Other generally includes items such as certain significant company-wide restructuring activities, including internal separation costs, and legacy costs or adjustments that relate to divested businesses that are no longer operated by Ashland. Reportable segment results Results of Ashland’s reportable segments are presented based on its management and internal accounting structure. The structure is specific to Ashland; therefore, the financial results of Ashland’s reportable segments are not necessarily comparable with similar information for other comparable companies. Ashland allocates all significant costs to its reportable segments except for certain significant company-wide restructuring activities, including stranded costs, and other costs or adjustments that relate to former businesses that Ashland no longer operates. The service cost component of pension and other postretirement benefits costs is allocated to each reportable segment on a ratable basis; while the remaining components of pension and other postretirement benefits costs are recorded within the other net periodic benefit income caption on the Statements of Consolidated Comprehensive Income (Loss). Ashland refines its expense allocation methodologies to the reportable segments from time to time as internal accounting practices are improved, more refined information becomes available and the industry or market changes. Significant revisions to Ashland’s methodologies are adjusted for all segments on a retrospective basis. The following table presents various financial information for each reportable segment for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions - unaudited) 2019 2018 2019 2018 SALES Specialty Ingredients $ 637 $ 646 $ 1,190 $ 1,196 Intermediates and Solvents 30 26 53 57 $ 667 $ 672 $ 1,243 $ 1,253 OPERATING INCOME (LOSS) Specialty Ingredients $ 70 $ 89 $ 96 $ 131 Intermediates and Solvents 5 3 5 6 Unallocated and other (31 ) (29 ) (64 ) (70 ) $ 44 $ 63 $ 37 $ 67

Subsequent Events

Subsequent Events	6 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	NOTE Q – SUBSEQUENT EVENTS On April 30, 2019, Ashland announced an intention to commence a $200 million share repurchase program under Ashland’s Board of Directors approved $1 billion stock repurchase program in fiscal 2018. Under the program, shares may be repurchased in privately negotiated and/or open market transactions, including under plans complying with Rule 10b5-1 of the Exchange Act. The $200 million repurchase will be the first repurchases made under the $1 billion program.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Basis of presentation The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and Securities and Exchange Commission (SEC) regulations. In the opinion of management, all adjustments considered necessary for a fair presentation have been included. Additionally, certain prior period data, primarily related to discontinued operations, have been reclassified in the Consolidated Financial Statements and accompanying notes to conform to the current period presentation, as further described in this section. These statements omit certain information and footnote disclosures required for complete annual financial statements and, therefore, should be read in conjunction with Ashland Global Holdings Inc.’s (Ashland or the Company) Annual Report on Form 10-K for the fiscal year ended September 30, 2018. Results of operations for the period ended March 31, 2019 are not necessarily indicative of the expected results for the remaining quarters in the fiscal year. On November 15, 2018, Ashland announced that it had signed a definitive agreement to sell substantially all of the assets and liabilities of its Composites segment and Intermediates and Solvents facility in Marl, Germany (Marl facility). This expected divestiture represents a strategic shift in Ashland's business and, in accordance with U.S. GAAP, qualified as a discontinued operation. As a result, the operating results and cash flows related to Composites and the Marl facility have been reflected as discontinued operations in the Statements of Consolidated Comprehensive Income (Loss) and Statements of Condensed Consolidated Cash Flows. The assets and liabilities that are to be sold have met the requirements to be classified within the Condensed Consolidated Balance Sheets under a held for sale designation. See Notes B and C for additional information on this expected divestiture. As a result of classifying the Composites reporting segment as a discontinued operation, Ashland is now comprised of two reportable segments: Specialty Ingredients and Intermediates and Solvents. The financial information reported for Intermediates and Solvents excludes the activity from the Marl facility due to the expected divestiture.
Use of Estimates, Risk and Uncertainties	Use of estimates, risks and uncertainties The preparation of Ashland’s Condensed Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosures of contingent assets and liabilities. Significant items that are subject to such estimates and assumptions include, but are not limited to, long-lived assets (including goodwill and other intangible assets), income taxes and liabilities and receivables associated with asbestos litigation and environmental remediation. Although management bases its estimates on historical experience and various other assumptions that are believed to be reasonable under the circumstances, actual results could differ significantly from the estimates under different assumptions or conditions. Ashland’s results are affected by domestic and international economic, political, legislative, regulatory and legal actions. Economic conditions, such as recessionary trends, inflation, interest and monetary exchange rates, government fiscal policies and changes in the prices of certain key raw materials, can have a significant effect on operations. While Ashland maintains reserves for anticipated liabilities and carries various levels of insurance, Ashland could be affected by civil, criminal, regulatory or administrative actions, claims or proceedings relating to asbestos, environmental remediation or other matters.
New Accounting Pronouncements	New accounting pronouncements A description of new U.S. GAAP accounting standards issued or adopted during the current year is required in interim financial reporting. A detailed listing of new accounting standards relevant to Ashland is included in the Annual Report on Form 10-K for the fiscal year ended September 30, 2018. The following standards relevant to Ashland were either issued or adopted in the current period or will become effective in a subsequent period. Revenue recognition In May 2014, the FASB issued accounting guidance outlining a single comprehensive five step model for entities to use in accounting for revenue arising from contracts with customers (ASC 606 Revenue from Contracts with Customers). The new guidance and subsequent amendments to it superseded most current revenue recognition guidance, in an effort to converge the revenue recognition principles within U.S. GAAP. This new guidance required entities to disclose certain quantitative and qualitative information regarding the nature, amount, timing and uncertainty of qualifying revenue and cash flows arising from contracts with customers. Entities had the option of using a full retrospective or a modified retrospective approach to adopt the new guidance. This guidance became effective for Ashland on October 1, 2018. Ashland formed an implementation team that evaluated the impact of the new standard on the Condensed Consolidated Financial Statements and the adoption method options available as well as the overall impact the new guidance would have on the organization. The assessment process consisted of categorizing Ashland’s revenue streams and reviewing the current internal accounting policies and practices to determine potential differences that could result from applying the requirements of the new standard to revenue contracts. Additional discussions and meetings with each revenue stream team occurred to solicit input, identify potential impacts and appropriate changes to Ashland’s business processes, systems and controls to support the revenue recognition and disclosure requirements under the new standard. Ashland elected to adopt this standard using the modified retrospective approach and determined that the overall impact was not material to the Condensed Consolidated Financial Statements. As a result, no cumulative-effect adjustment was made to retained earnings in the Condensed Consolidated Balance Sheets. Leases In February 2016, the FASB issued new accounting guidance related to lease transactions. The main objective of this guidance is to increase transparency and comparability among organizations by requiring lessees to recognize assets and liabilities on the balance sheet for the right to use assets and obligations created by leases and to disclose key information about leasing arrangements. The presentation of the Statements of Consolidated Comprehensive Income (Loss) and the Statements of Condensed Consolidated Cash Flows is largely unchanged under this guidance. This guidance retains a distinction between finance leases and operating leases, and the classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in the current accounting literature. The guidance will become effective for Ashland on October 1, 2019 and it will have a significant effect on Ashland’s Condensed Consolidated Balance Sheet and disclosures. In July 2018, the FASB amended this guidance to give entities the option to apply the standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Ashland currently intends to utilize this transition method upon adopting the guidance. Ashland has formed an implementation team and is quantifying the impact that this guidance will have within its Condensed Consolidated Financial Statements. Other accounting pronouncements In January 2016, the FASB issued accounting guidance related to the recognition and measurement as well as the presentation and disclosures for certain financial instruments. Most notably, the guidance requires entities to measure equity investments at fair value and to recognize any changes in fair value in net income rather than accumulated other comprehensive income (AOCI). The guidance became effective for Ashland on October 1, 2018 and resulted in Ashland recording a cumulative-effect adjustment to reclassify net after-tax unrealized gains of $34 million on its equity securities from AOCI to retained earnings. In the current period, the adoption of this guidance resulted in a significant impact to net income as Ashland recognized investment gains of $27 million for the three months ended March 31, 2019 and investment losses of $3 million for the six months ended March 31, 2019 within the net interest and other expense (income) caption on the Statement of Consolidated Comprehensive Income (Loss). The impact of this new guidance could continue to have a material impact on Ashland’s Statements of Consolidated Comprehensive Income (Loss) in prospective periods depending on the fluctuations of unrealized gains and losses within the investment securities portfolio. For current and future periods, the changes in fair value of the equity securities will no longer be classified within other comprehensive income under the new guidance. For further information on Ashland’s equity securities, see Note E. In October 2016, the FASB issued new accounting guidance which requires entities to recognize the income tax effects of intercompany transfers of assets other than inventory when the transfer occurs. This guidance eliminates the exception under previous U.S. GAAP that the income tax effects of all intercompany transfers of assets other than inventory be deferred until the assets are sold to a third party or otherwise recovered through use. This guidance became effective for Ashland on October 1, 2018 and was applied using a modified retrospective approach. Consequently, Ashland recorded a cumulative-effect adjustment to reclassify less than $1 million from other current assets and deferred taxes to retained earnings.
Fair Value of Financial Instruments Policy	As required by U.S. GAAP, Ashland uses applicable guidance for defining fair value, the initial recording and periodic remeasurement of certain assets and liabilities measured at fair value and related disclosures for instruments measured at fair value. Fair value accounting guidance establishes a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). An instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the instrument’s fair value measurement. The three levels within the fair value hierarchy are described as follows. Level 1 – Observable inputs such as unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3 – Unobservable inputs for the asset or liability for which there is little, if any, market activity at the measurement date. Unobservable inputs reflect Ashland’s own assumptions about what market participants would use to price the asset or liability. The inputs are developed based on the best information available in the circumstances, which might include Ashland’s own financial data such as internally developed pricing models, discounted cash flow methodologies, as well as instruments for which the fair value determination requires significant management judgment. For assets that are measured using quoted prices in active markets (Level 1), the total fair value is the published market price per unit multiplied by the number of units held without consideration of transaction costs. Assets and liabilities that are measured using significant other observable inputs (Level 2) are primarily valued by reference to quoted prices of similar assets or liabilities in active markets, adjusted for any terms specific to that asset or liability. For all other assets and liabilities for which unobservable inputs are used (Level 3), fair value is derived using fair value models, such as a discounted cash flow model or other standard pricing models that Ashland deems reasonable.
Inventories	Inventories are carried at the lower of cost or net realizable value. Inventories are primarily stated at cost using the weighted-average cost method. In addition, certain inventories are valued at cost using the last-in, first-out (LIFO) method.
Goodwill and Intangible Assets, Goodwill	Ashland reviews goodwill and indefinite-lived intangible assets for impairment annually or when events and circumstances indicate an impairment may have occurred. This annual assessment is performed as of July 1 and consists of Ashland determining each reporting unit’s current fair value compared to its current carrying value. For its July 1, 2018 assessment, Ashland determined that its reporting units for the allocation of goodwill were its three reportable segments: Specialty Ingredients, Composites and Intermediates and Solvents. At that time, Ashland determined no additional impairment existed. Due to the expected divestiture of the Composites reporting unit, Ashland has two remaining reporting units as of March 31, 2019: Specialty Ingredients and Intermediates and Solvents. See Note B for more information on the expected divestiture.
Finite-Lived Intangible Asset	Intangible assets principally consist of trademarks and trade names, intellectual property and customer and supplier relationships. Intangible assets classified as finite are amortized on a straight-line basis over their estimated useful lives. The cost of trademarks and trade names is amortized principally over 3 to 25 years, intellectual property over 5 to 25 years, and customer and supplier relationships over 3 to 24 years.
Goodwill and Intangible Assets, Intangible Assets, Indefinite-Lived	Ashland annually reviews indefinite-lived intangible assets for possible impairment or whenever events or changes in circumstances indicate that carrying amounts may not be recoverable.
Commitments and Contingencies Policy	Ashland and Hercules have liabilities from claims alleging personal injury caused by exposure to asbestos. To assist in developing and annually updating independent reserve estimates for future asbestos claims and related costs given various assumptions, Ashland retained Nathan Associates Inc. (Nathan). The methodology used by Nathan to project future asbestos costs is based largely on recent experience, including claim-filing and settlement rates, disease mix, enacted legislation, open claims and litigation defense. The claim experience of Ashland and Hercules are separately compared to the results of previously conducted third party epidemiological studies estimating the number of people likely to develop asbestos-related diseases. Those studies were undertaken in connection with national analyses of the population expected to have been exposed to asbestos. Using that information, Nathan estimates a range of the number of future claims that may be filed, as well as the related costs that may be incurred in resolving those claims. Changes in asbestos-related liabilities and receivables are recorded on an after-tax basis within the discontinued operations caption in the Statements of Consolidated Comprehensive Income (Loss).
Environmental Cost Policy	The total reserves for environmental remediation reflect Ashland’s estimates of the most likely costs that will be incurred over an extended period to remediate identified conditions for which the costs are reasonably estimable, without regard to any third-party recoveries. Engineering studies, probability techniques, historical experience and other factors are used to identify and evaluate remediation alternatives and their related costs in determining the estimated reserves for environmental remediation. Ashland continues to discount certain environmental sites and regularly adjusts its reserves as environmental remediation continues. Ashland has estimated the value of its probable insurance recoveries associated with its environmental reserve based on management’s interpretations and estimates surrounding the available or applicable insurance coverage.
Earnings Per Share	The following is the computation of basic and diluted earnings per share (EPS) from continuing operations attributable to Ashland. Stock appreciation rights (SARs), stock options and warrants available to purchase shares outstanding for each reporting period whose grant price was greater than the average market price of Ashland Common Stock for each applicable period were not included in the computation of income from continuing operations per diluted share because the effect of these instruments would be antidilutive. The total number of these shares outstanding was approximately 1.0 million and 0.7 million at March 31, 2019 and 2018, respectively. Earnings per share is reported under the treasury stock method.
Stock Incentive Plan Policy	Ashland has stock incentive plans under which key employees or directors are granted stock appreciation rights (SARs), performance awards or nonvested stock awards. Each program is typically a long-term incentive plan designed to link employee compensation with increased shareholder value or reward superior performance and encourage continued employment with Ashland. Ashland recognizes compensation expense for the grant date fair value of stock-based awards over the applicable vesting period.
Segment Reporting	Ashland determines its reportable segments based on how operations are managed internally for the products and services sold to customers, including how the results are reviewed by the chief operating decision maker, which includes determining resource allocation methodologies used for reportable segments. Operating income is the primary measure on the Statements of Consolidated Comprehensive Income (Loss) that is reviewed by the chief operating decision maker in assessing each reportable segment's financial performance. Ashland does not aggregate operating segments to arrive at these reportable segments.

Divestitures (Tables)

Divestitures (Tables)	6 Months Ended
	Mar. 31, 2019
Divestitures [Abstract]
Summary of Assets and Liabilities Held for Sale	The assets and liabilities of Composites and the Marl facility along with other corporate asset divestitures for current and prior periods have been reflected as assets and liabilities held for sale. As a result, in accordance with U.S. GAAP standards, depreciation and amortization are no longer being recorded within the Statements of Consolidated Comprehensive Income (Loss) and the Condensed Consolidated Balance Sheets. These assets and liabilities are comprised of the following components: March 31 September 30 (In millions) 2019 2018 Accounts receivable, net (a) $ 173 $ 159 Inventories 67 67 Net property, plant and equipment 254 — Goodwill 143 — Intangibles 38 — Deferred income taxes 7 — Other assets 57 14 Current assets held for sale $ 739 $ 240 Net property, plant and equipment $ — $ 254 Goodwill — 144 Intangibles — 40 Deferred income taxes — 7 Other assets — 32 Noncurrent assets held for sale $ — $ 477 Trade and other payables $ 112 $ 152 Employee benefit obligations 22 — Accrued expenses and other liabilities 10 11 Other liabilities 3 — Current liabilities held for sale $ 147 $ 163 Employee benefit obligations — 23 Other liabilities — 3 Noncurrent liabilities held for sale $ — $ 26 (a) Accounts receivable included an allowance for doubtful accounts of $3 million at both March 31, 2019 and September 30, 2018.

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Mar. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
Components of Consolidated Comprehensive Income (Loss) Related to Discontinued Operations	Components of amounts reflected in the Statements of Consolidated Comprehensive Income (Loss) related to discontinued operations are presented in the following table for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Income (loss) from discontinued operations (net of tax) Composites/Marl facility $ 28 $ 24 $ 53 $ 49 Valvoline 1 4 1 7 Asbestos-related litigation — 3 — 3 Water Technologies 2 — 1 — Distribution — — (1 ) — $ 31 $ 31 $ 54 $ 59 The following table presents a reconciliation of the captions within Ashland's Statements of Consolidated Comprehensive Income (Loss) for the income (loss) from discontinued operations attributable to Composites and the Marl facility for the three and six months ended March 31, 2019 and 2018. Interest expense was allocated to discontinued operations based on Ashland’s mandatory debt prepayments upon the disposition of Composites and the Marl facility. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Income (loss) from discontinued operations attributable to Composites/Marl facility Sales $ 284 $ 302 $ 559 $ 563 Cost of sales (217 ) (250 ) (434 ) (461 ) Selling, general and administrative expense (19 ) (17 ) (41 ) (34 ) Research and development expense (3 ) (3 ) (6 ) (5 ) Equity and other income (expense) — (1 ) 3 2 Pretax operating income of discontinued operations 45 31 81 65 Net interest and other (expense) income (6 ) (5 ) (12 ) (9 ) Pretax income of discontinued operations 39 26 69 56 Income tax expense (11 ) (2 ) (16 ) (7 ) Income from discontinued operations $ 28 $ 24 $ 53 $ 49

Restructuring Activities (Table

Restructuring Activities (Tables)	6 Months Ended
	Mar. 31, 2019
Restructuring And Related Activities [Abstract]
Summary of Amount of Restructuring Reserves Related to Program	The following table details at March 31, 2019, the amount of restructuring reserves related to the programs discussed above, and the related activity in these reserves during the six months ended March 31, 2019. The severance and facility cost reserves were primarily recorded within accrued expenses and other liabilities in the Condensed Consolidated Balance Sheet as of March 31, 2019. (In millions) Severance costs Facility costs Total Balance as of September 30, 2018 36 7 43 Restructuring reserve 4 8 12 Utilization (cash paid) (18 ) (5 ) (23 ) Balance as of March 31, 2019 $ 22 $ 10 32

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Subject to Recurring Fair Value Measurements	The following table summarizes financial instruments subject to recurring fair value measurements as of March 31, 2019. Carrying Total fair Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs (In millions) value value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 164 $ 164 $ 164 $ — $ — Restricted investments (a) 326 326 326 — — Deferred compensation investments (b) 166 166 — 166 — Investment of captive insurance company 4 4 4 — — Foreign currency derivatives 3 3 — 3 — Total assets at fair value $ 663 $ 663 $ 494 $ 169 $ — Liabilities Foreign currency derivatives $ 3 $ 3 $ — $ 3 $ — (a) Included in restricted investments is $30 million classified in the other current assets caption on the Condensed Consolidated Balance Sheets. (b) Included in other noncurrent assets in the Condensed Consolidated Balance Sheets. The following table summarizes financial asset instruments subject to recurring fair value measurements as of September 30, 2018. Carrying Total fair Quoted prices in active markets for identical assets Significant other observable inputs Significant unobservable inputs (In millions) value value Level 1 Level 2 Level 3 Assets Cash and cash equivalents $ 294 $ 294 $ 294 $ — $ — Restricted investments (a) 342 342 342 — — Deferred compensation investments (b) 165 165 — 165 — Investment of captive insurance company 3 3 3 — — Foreign currency derivatives 11 11 — 11 — Total assets at fair value $ 815 $ 815 $ 639 $ 176 $ — Liabilities Foreign currency derivatives $ 3 $ 3 $ — $ 3 $ — (a) Included in restricted investments is $30 million classified in the other current assets caption on the Condensed Consolidated Balance Sheets. (b) Included in other noncurrent assets in the Condensed Consolidated Balance Sheets.
Summary of Investment Portfolio	The following table provides a summary of the activity within the investment portfolio as of March 31, 2019 and September 30, 2018: (In millions) March 31 2019 September 30 2018 Original cost $ 335 $ 335 Accumulated adjustments, net (47 ) (38 ) Adjusted cost, beginning of year (a) 288 297 Investment income (b) 5 8 Net unrealized gain (c) 25 54 Realized gains (c) 26 6 Settlement funds 2 10 Disbursements (20 ) (33 ) Fair value $ 326 $ 342 (a) The accumulated adjustments include investment income, realized gains, disbursements and settlements recorded in previous periods. (b) Investment income for the demand deposit includes interest income as well as dividend income transferred from the equity and corporate bond mutual funds. (c) Presented under the original cost method. The following table presents gross unrealized gains and losses for the restricted investment securities as of March 31, 2019 and September 30, 2018: Gross Gross (In millions) Adjusted Cost Unrealized Gain Unrealized Loss Fair Value As of March 31, 2019 Demand deposit $ 164 $ — $ — $ 164 Equity mutual fund 71 25 — 96 Corporate bond mutual fund 66 — — 66 Fair value $ 301 $ 25 $ — $ 326 As of September 30, 2018 Demand deposit $ 20 $ — $ — $ 20 Equity mutual fund 148 59 — 207 Corporate bond mutual fund 120 — (5 ) 115 Fair value $ 288 $ 59 $ (5 ) $ 342
Summary of Investment Income, Realized Gains and Disbursements Related to Investments	The following table presents the investment income, net unrealized gains and losses, realized gains and disbursements related to the investments within the portfolio for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Investment income $ 2 $ 2 $ 5 $ 4 Net unrealized gains (losses) (a) 27 (8 ) (3 ) 2 Realized gains (b) — 3 — 4 Disbursements (12 ) (12 ) (20 ) (17 ) (a) Ashland determined that all unrealized gains and losses were related to equity securities with readily determinable fair values. Due to the new accounting guidance adopted in the first quarter of fiscal year 2019, the net unrealized losses during the three and six months ended March 31, 2019 were recorded within the net interest and other expense (income) caption in the Statements of Consolidated Comprehensive Income (Loss). In 2018 these net unrealized gains (losses) were in AOCI. (b) Relates only to the three and six months ended March 31, 2018 prior to the adoption of the new accounting guidance for equity securities.
Summary of Net Gains and Losses on Foreign Currency Derivatives	The following table summarizes the net gains and losses recognized during the three and six months ended March 31, 2019 and 2018 within the Statements of Consolidated Comprehensive Income (Loss). Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Foreign currency derivative gains (losses) $ 3 $ (16 ) $ 4 $ (27 )
Summary of Fair Values of Outstanding Foreign Currency Derivatives	The following table summarizes the fair values of the outstanding foreign currency derivatives as of March 31, 2019 and September 30, 2018 included in accounts receivable and accrued expenses and other liabilities of the Condensed Consolidated Balance Sheets. March 31 September 30 (In millions) 2019 2018 Foreign currency derivative assets $ 3 $ 11 Notional contract values 319 1,209 Foreign currency derivative liabilities $ 3 $ 3 Notional contract values 378 755

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Summary of Inventories	The following table summarizes Ashland’s inventories as of the reported Condensed Consolidated Balance Sheet dates. (In millions) March 31, 2019 September 30, 2018 Finished products $ 378 $ 381 Raw materials, supplies and work in process 221 215 $ 599 $ 596

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	6 Months Ended
	Mar. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Goodwill by Reportable Segment	The following is a progression of goodwill by reportable segment for the six months ended March 31, 2019. Specialty Intermediates (In millions) Ingredients and Solvents (a) Total Balance at September 30, 2018 $ 2,304 $ — $ 2,304 Acquisitions — — — Currency translation (25 ) — (25 ) Balance at March 31, 2019 $ 2,279 $ — $ 2,279 (a) As of March 31, 2019 and September 30, 2018, there was accumulated impairment of $90 million related to the Intermediates and Solvents reportable segment.
Summary of Intangible Assets	Intangible assets were comprised of the following as of March 31, 2019 and September 30, 2018. March 31, 2019 Gross Net carrying Accumulated carrying (In millions) amount amortization amount Definite-lived intangibles Trademarks and trade names $ 66 $ (27 ) $ 39 Intellectual property 715 (370 ) 345 Customer and supplier relationships 750 (277 ) 473 Total definite-lived intangibles 1,531 (674 ) 857 Indefinite-lived intangibles Trademarks and trade names 278 — 278 Total intangible assets $ 1,809 $ (674 ) $ 1,135 September 30, 2018 Gross Net carrying Accumulated carrying (In millions) amount amortization amount Definite-lived intangibles Trademarks and trade names $ 66 $ (25 ) $ 41 Intellectual property 721 (350 ) 371 Customer and supplier relationships 759 (264 ) 495 Total definite-lived intangibles 1,546 (639 ) 907 Indefinite-lived intangibles Trademarks and trade names 278 — 278 Total intangible assets $ 1,824 $ (639 ) $ 1,185

Debt (Tables)

Debt (Tables)	6 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Summary of Current and Long-term Debt	The following table summarizes Ashland’s current and long-term debt as of the dates reported in the Condensed Consolidated Balance Sheets. (In millions) March 31, 2019 September 30, 2018 4.750% notes, due 2022 $ 1,083 $ 1,083 Term Loan B, due 2024 590 593 6.875% notes, due 2043 376 376 Term Loan A, due 2022 195 195 Accounts receivable securitizations 207 195 6.50% junior subordinated notes, due 2029 53 52 Revolving credit facility 25 25 Medium-term notes, due 2019, interest of 9.4% — 5 Other (a) 7 5 Total debt 2,536 2,529 Short-term debt (includes current portion of long-term debt) (261 ) (254 ) Long-term debt (less current portion) $ 2,275 $ 2,275 (a) Includes $19 million and $21 million of debt issuance cost discounts as of March 31, 2019 and September 30, 2018, respectively, in addition to a European short-term loan facility with an outstanding balance of $23 million at both March 31, 2019 and September 30, 2018.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Summary of Changes in Unrecognized Tax Benefits	Changes in unrecognized tax benefits are summarized as follows for the six months ended March 31, 2019. (In millions) Balance at October 1, 2018 $ 164 Decreases related to positions taken on items from prior years (3 ) Increases related to positions taken in the current year 3 Lapse of statute of limitations (2 ) Balance at March 31, 2019 $ 162

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Mar. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Schedule of Components of Pension and Other Postretirement Benefit Costs for Continuing Operation	The following table details the components of pension and other postretirement benefit costs for continuing operations. Pension benefits Other postretirement benefits (In millions) 2019 2018 2019 2018 Three months ended March 31 Service cost $ 1 $ 2 $ — $ — Interest cost 2 2 1 — Expected return on plan assets (2 ) (3 ) — — Curtailment — — — — Actuarial (gain) loss — — — — Total net periodic benefit costs $ 1 $ 1 $ 1 $ — Six months ended March 31 Service cost $ 3 $ 4 $ — $ 1 Interest cost 5 5 1 — Expected return on plan assets (5 ) (6 ) — — Curtailment (18 ) — — — Actuarial gain — — — — Total net periodic benefit costs (income) $ (15 ) $ 3 $ 1 $ 1

Litigation, Claims and Contin_2

Litigation, Claims and Contingencies (Tables)	6 Months Ended
	Mar. 31, 2019
Loss Contingencies [Line Items]
Reconciliation of Changes in Environmental Contingencies and Asset Retirement Obligations Reserve	The following table provides a reconciliation of the changes in the environmental remediation reserves during the six months ended March 31, 2019 and 2018. Six months ended March 31 (In millions) 2019 2018 Reserve - beginning of period $ 187 $ 163 Disbursements (15 ) (16 ) Revised obligation estimates and accretion 7 17 Reserve - end of period $ 179 $ 164
Components of Environmental Remediation Expense	Components of environmental remediation expense included within the selling, general and administrative expense caption of the Statements of Consolidated Comprehensive Income (Loss) are presented in the following table for the three months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Environmental expense $ 3 $ 4 $ 6 $ 16 Accretion 1 — 1 1 Legal expense 2 2 3 3 Total expense 6 6 10 20 Insurance receivable (a) — (1 ) (1 ) (1 ) Total expense, net of receivable activity (b) $ 6 $ 5 $ 9 $ 19 (a) Activity of $0 denotes value less than $1 million. (b) Net expense of $1 million and $2 million for the three and six months ended March 31, 2019, and $1 million for both the three and six months ended March 31, 2018, relates to divested businesses which qualified for treatment as discontinued operations for which certain environmental liabilities were retained by Ashland. These amounts are classified within the income from discontinued operations caption of the Statements of Consolidated Comprehensive Income (loss).
Ashland [Member]
Loss Contingencies [Line Items]
Summary of Asbestos Claims Activity	A summary of Ashland asbestos claims activity, excluding Hercules claims, follows. Six months ended March 31 Years ended September 30 (In thousands) 2019 2018 2018 2017 2016 Open claims - beginning of year 53 54 54 57 60 New claims filed 1 1 2 2 2 Claims settled — — (1 ) (1 ) — Claims dismissed (1 ) (2 ) (2 ) (4 ) (5 ) Open claims - end of period 53 53 53 54 57
Progression of Activity in Asbestos Reserve Accounts	A progression of activity in the asbestos reserve is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Asbestos reserve - beginning of year $ 380 $ 419 $ 419 $ 415 $ 409 Reserve adjustment — — (8 ) 36 37 Amounts paid (14 ) (17 ) (31 ) (32 ) (31 ) Asbestos reserve - end of period (a) $ 366 $ 402 $ 380 $ 419 $ 415 (a) Includes $31 million and $30 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2019 and September 30, 2018, respectively.
Progression of Insurance Receivable	A progression of activity in the Ashland insurance receivable is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Insurance receivable - beginning of year $ 140 $ 155 $ 155 $ 151 $ 150 Receivable adjustment — — (5 ) 15 16 Insurance settlement — — — (5 ) (4 ) Amounts collected (4 ) (6 ) (10 ) (6 ) (11 ) Insurance receivable - end of period (a) $ 136 $ 149 $ 140 $ 155 $ 151
Hercules [Member]
Loss Contingencies [Line Items]
Summary of Asbestos Claims Activity	A summary of Hercules’ asbestos claims activity follows. Six months ended March 31 Years ended September 30 (In thousands) 2019 2018 2018 2017 2016 Open claims - beginning of year 13 12 12 15 20 New claims filed — 1 2 1 1 Claims dismissed (1 ) (1 ) (1 ) (4 ) (6 ) Open claims - end of period 12 12 13 12 15
Progression of Activity in Asbestos Reserve Accounts	A progression of activity in the asbestos reserve is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Asbestos reserve - beginning of year $ 282 $ 323 $ 323 $ 321 $ 311 Reserve adjustments — — (19 ) 16 25 Amounts paid (10 ) (12 ) (22 ) (14 ) (15 ) Asbestos reserve - end of period (a) $ 272 $ 311 $ 282 $ 323 $ 321 (a) Included $20 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018.
Progression of Insurance Receivable	A progression of activity in the Hercules insurance receivable is presented in the following table. Six months ended March 31 Years ended September 30 (In millions) 2019 2018 2018 2017 2016 Insurance receivable - beginning of year $ 54 $ 68 $ 68 $ 63 $ 56 Receivable adjustment — — (14 ) 5 7 Insurance receivable - end of period $ 54 $ 68 $ 54 $ 68 $ 63

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings per Share	The following is the computation of basic and diluted earnings per share (EPS) from continuing operations attributable to Ashland. Stock appreciation rights (SARs), stock options and warrants available to purchase shares outstanding for each reporting period whose grant price was greater than the average market price of Ashland Common Stock for each applicable period were not included in the computation of income from continuing operations per diluted share because the effect of these instruments would be antidilutive. The total number of these shares outstanding was approximately 1.0 million and 0.7 million at March 31, 2019 and 2018, respectively. Earnings per share is reported under the treasury stock method. Three months ended Six months ended March 31 March 31 (In millions, except per share data) 2019 2018 2019 2018 Numerator Numerator for basic and diluted EPS - Income (loss) from continuing operations $ 45 $ 42 $ (26 ) $ 10 Denominator Denominator for basic EPS - Weighted- average common shares outstanding 63 63 63 63 Share based awards convertible to common shares (a) 1 1 — 1 Denominator for diluted EPS - Adjusted weighted- average shares and assumed conversions 64 64 63 64 EPS from continuing operations Basic $ 0.72 $ 0.66 $ (0.41 ) $ 0.15 Diluted 0.71 0.65 (0.41 ) 0.15 (a) As a result of the loss from continuing operations attributable to Ashland during the six months ended March 31, 2019, the effect of the share-based awards convertible to common shares would be antidilutive. In accordance with U.S. GAAP, these shares have been excluded from the diluted EPS calculation.

Equity Items (Tables)

Equity Items (Tables)	6 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	Components of other comprehensive income (loss) recorded in the Statements of Consolidated Comprehensive Income (Loss) are presented below, before tax and net of tax effects. 2019 2018 (In millions) Before tax Tax (expense) benefit Net of tax Before tax Tax (expense) benefit Net of tax Three months ended March 31 Other comprehensive income (loss) Unrealized translation gain (loss) $ (9 ) $ — $ (9 ) $ 55 $ — $ 55 Pension and postretirement obligation adjustment: Adjustment of unrecognized prior service costs — — — — — — Net change in investment securities: Unrealized gains during periods (a) — — — (5 ) 1 (4 ) Reclassification adjustment for gains included in net income — — — (3 ) 1 (2 ) Total other comprehensive income (loss) $ (9 ) $ — $ (9 ) $ 47 $ 2 $ 49 Six months ended March 31 Other comprehensive income (loss) Unrealized translation gain (loss) $ (40 ) $ — $ (40 ) $ 58 $ — $ 58 Pension and postretirement obligation adjustment: Adjustment of unrecognized prior service costs (7 ) 1 (6 ) — — — Net change in investment securities: Unrealized gains during periods (a) — — — 6 (1 ) 5 Reclassification adjustment for gains included in net income — — — (4 ) 1 (3 ) Total other comprehensive income (loss) $ (47 ) $ 1 $ (46 ) $ 60 $ — $ 60 ( a )
Summary of Reconciliation of Changes in Stockholders' Equity	A reconciliation of changes in stockholders’ equity are as follows: Three months ended Six months ended March 31 March 31 (In millions) 2019 2018 2019 2018 Common stock and paid in capital Balance, beginning of period $ 948 $ 932 $ 947 $ 932 Common shares issued under stock incentive and other plans (a) 5 4 6 4 Balance, end of period 953 936 953 936 Retained earnings Balance, beginning of period 2,719 2,678 2,750 2,696 Adoption of new accounting pronouncements (b) 1 — 34 — Net income (loss) 76 73 28 69 Regular dividends (16 ) (14 ) (32 ) (28 ) Balance, end of period 2,780 2,737 2,780 2,737 Accumulated other comprehensive income (loss) Balance, beginning of period (362 ) (211 ) (291 ) (222 ) Adoption of new accounting pronouncements (b) — — (34 ) — Unrealized translation gain (loss) (9 ) 55 (40 ) 58 Pension and postretirement obligation adjustment — — (6 ) — Net change in investment securities — (6 ) — 2 Balance, end of period (371 ) (162 ) (371 ) (162 ) Total stockholders' equity $ 3,362 $ 3,511 $ 3,362 $ 3,511 Cash dividends declared per common share $ 0.25 $ 0.225 $ 0.50 $ 0.45 (a) Common share issued were 93,738 and 154,421 for the three months ended March 31, 2019 and 2018 and 234,352 and 265,821 for the six months ended March 31, 2019 and 2018. (b) Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and tax effects of intercompany transfers during fiscal 2019. See Note A for more information.

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	6 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Components of Stock-Based Compensation Expense Included in Continuing Operations	The components of Ashland’s pre-tax stock-based compensation expense included in continuing operations are as follows: Three months ended Six months ended March 31 March 31 (In millions) 2019 (a) 2018 (b) 2019 (a) 2018 (b) SARs $ 2 $ 2 $ 4 $ 3 Nonvested stock awards 6 5 10 11 Performance share awards 2 2 2 6 $ 10 $ 9 $ 16 $ 20 (a) Included $2 million and $3 million of expense related to cash-settled nonvested restricted stock awards during the three and six months ended March 31, 2019 and $2 million of expense related to cash-settled performance units during the three ended March 31, 2019. (b) Included $2 million and $4 million of expense related to cash-settled nonvested restricted stock awards and $1 million and $3 million of expense related to cash-settled performance units during the three and six months ended March 31, 2018, respectively.

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Mar. 31, 2019
Revenue From Contract With Customer [Abstract]
Disaggregation of Revenue	Ashland disaggregates its revenue from contracts with customers by segment, geographical region and product category, as Ashland believes these categories best depict how management reviews the financial performance of its operations for the three and six months ended March 31, 2018 and 2019. See the following tables for details: Sales by geography (In millions) Specialty Ingredients Intermediates and Solvents Geography 2019 2018 2019 2018 Three months ended March 31 North America $ 247 $ 258 $ 15 $ 13 Europe 220 222 6 6 Asia Pacific 115 111 7 6 Latin America & other 55 55 2 1 $ 637 $ 646 $ 30 $ 26 Six months ended March 31 North America $ 466 $ 481 $ 26 $ 27 Europe 390 389 11 13 Asia Pacific 231 218 13 14 Latin America & other 103 108 3 3 $ 1,190 $ 1,196 $ 53 $ 57 Sales by product category (In millions) 2019 2018 Three months ended March 31 Ashland Specialty Ingredients Cellulosics $ 224 $ 215 Poly-vinyl pyrrolidones 110 115 Adhesives 89 90 Actives 43 42 Vinyl ethers 31 38 Pharmachem 64 63 Other 76 83 $ 637 $ 646 Intermediates and Solvents Derivatives $ 25 $ 21 Butanediol 5 5 $ 30 $ 26 Total $ 667 $ 672 Sales by product category (In millions) 2019 2018 Six months ended March 31 Ashland Specialty Ingredients Cellulosics $ 413 $ 393 Poly-vinyl pyrrolidones 205 210 Adhesives 171 169 Actives 80 80 Vinyl ethers 55 66 Pharmachem 123 121 Other 143 157 $ 1,190 $ 1,196 Intermediates and Solvents Derivatives $ 45 $ 48 Butanediol 8 9 $ 53 $ 57 Total $ 1,243 $ 1,253

Reportable Segment Information

Reportable Segment Information (Tables)	6 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Summary of Financial Information for Each Reportable Segment	The following table presents various financial information for each reportable segment for the three and six months ended March 31, 2019 and 2018. Three months ended Six months ended March 31 March 31 (In millions - unaudited) 2019 2018 2019 2018 SALES Specialty Ingredients $ 637 $ 646 $ 1,190 $ 1,196 Intermediates and Solvents 30 26 53 57 $ 667 $ 672 $ 1,243 $ 1,253 OPERATING INCOME (LOSS) Specialty Ingredients $ 70 $ 89 $ 96 $ 131 Intermediates and Solvents 5 3 5 6 Unallocated and other (31 ) (29 ) (64 ) (70 ) $ 44 $ 63 $ 37 $ 67

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Details) $ in Millions		Jul. 01, 2018ReportableSegment	Mar. 31, 2019USD ($)	Mar. 31, 2019USD ($)ReportableSegment
Significant Accounting Policies [Line Items]
Number of reportable segments | ReportableSegment		3		2
Recognition of investment gain (loss) within net interest and other expense (income)			$ 27	$ (3)
Accounting Standards Update 2016-16 [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Cumulative-effect adjustment, reclassification from other current assets and deferred taxes to retained earnings			$ 1	1
Accumulated other comprehensive income (loss) [Member]
Significant Accounting Policies [Line Items]
Unrealized gains on equity securities on reclassification from AOCI to retained earnings	[1],[2]			$ 34
[1]	At March 31, 2019 and September 30, 2018, the after-tax accumulated other comprehensive loss attributable to Ashland of $371 million and $291 million, respectively, was each comprised of net unrealized translation losses of $368 million and $328 million, respectively, net unrealized gains on investment securities of zero and $34 million, respectively, and unrecognized prior service costs as a result of certain employee benefit plan amendments of $3 million and unrecognized prior services credits of $3 million, respectively.
[2]	Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and the tax effects of intercompany transfers during fiscal 2019. See Note A for more information.

Divestitures - Additional Infor

Divestitures - Additional Information (Details) - USD ($) $ in Millions	Nov. 15, 2018	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stranded divestitures costs		$ 12	$ 12	$ 23	$ 23
Property, plant and equipment		1,587		1,587		$ 1,646
Impairment charge		5
Composites Segment and the Intermediates and Solvents Facility [Member] | Land and Buildings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment		$ 6		$ 6		$ 9
Composites Segment and the Intermediates and Solvents Facility [Member] | INEOS Enterprises [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transaction value in sale of business	$ 1,100
Expected net proceeds from sale of business	$ 1,000

Divestitures - Summary of Asset

Divestitures - Summary of Assets and Liabilities Held for Sale (Details) - USD ($) $ in Millions		Mar. 31, 2019	Sep. 30, 2018
Divestitures [Abstract]
Accounts receivable, net	[1]	$ 173	$ 159
Inventories		67	67
Net property, plant and equipment		254
Goodwill		143
Intangibles		38
Deferred income taxes		7
Other assets		57	14
Current assets held for sale		739	240
Net property, plant and equipment			254
Goodwill			144
Intangibles			40
Deferred income taxes			7
Other assets			32
Noncurrent assets held for sale			477
Trade and other payables		112	152
Employee benefit obligations		22
Accrued expenses and other liabilities		10	11
Other liabilities		3
Current liabilities held for sale		$ 147	163
Employee benefit obligations			23
Other liabilities			3
Noncurrent liabilities held for sale			$ 26
[1]	Accounts receivable included an allowance for doubtful accounts of $3 million at both March 31, 2019 and September 30, 2018.

Divestitures - Summary of Ass_2

Divestitures - Summary of Assets and Liabilities Held for Sale (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Divestitures [Abstract]
Allowance for doubtful accounts	$ 3	$ 3

Discontinued Operations - Compo

Discontinued Operations - Components of Consolidated Comprehensive Income (Loss) Related to Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)	$ 31	$ 31	$ 54	$ 59
Composites/Marl facility [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)	28	24	53	49
Valvoline [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)	1	4	1	7
Asbestos [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)		$ 3		$ 3
Water Technologies [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)	$ 2		1
Distribution [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations (net of tax)			$ (1)

Discontinued Operations - Recon

Discontinued Operations - Reconciliation of Consolidated Income (Loss) From Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income (loss) from discontinued operations attributable to Composites/Marl facility
Income from discontinued operations	$ 31	$ 31	$ 54	$ 59
Composites/Marl facility [Member]
Income (loss) from discontinued operations attributable to Composites/Marl facility
Sales	284	302	559	563
Cost of sales	(217)	(250)	(434)	(461)
Selling, general and administrative expense	(19)	(17)	(41)	(34)
Research and development expense	(3)	(3)	(6)	(5)
Equity and other income (expense)		(1)	3	2
Pretax operating income of discontinued operations	45	31	81	65
Net interest and other (expense) income	(6)	(5)	(12)	(9)
Pretax income of discontinued operations	39	26	69	56
Income tax expense	(11)	(2)	(16)	(7)
Income from discontinued operations	$ 28	$ 24	$ 53	$ 49

Restructuring Activities - Addi

Restructuring Activities - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring reserve	$ 32,000,000	$ 43,000,000		$ 32,000,000
Severance Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve	22,000,000	36,000,000		22,000,000
Facility Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve	10,000,000	7,000,000		10,000,000
Restructuring costs	1,000,000		$ 0	8,000,000	$ 0
Voluntary Severance Offer [Member]
Restructuring Cost And Reserve [Line Items]
Severance costs		$ 36,000,000
Voluntary Severance Offer [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Severance costs	0			4,000,000
Plant Restructuring [Member] | Severance Costs [Member] | Specialty Ingredients [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve	5,000,000			5,000,000
Restructuring costs				5,000,000
Plant Restructuring [Member] | Accelerated Depreciation and Amortization [Member] | Specialty Ingredients [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs				38,000,000
Plant Restructuring [Member] | Plant Closure Costs [Member] | Specialty Ingredients [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve	4,000,000			4,000,000
Restructuring costs				4,000,000
Plant Restructuring [Member] | Cost of Sales [Member] | Specialty Ingredients [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 20,000,000			$ 47,000,000

Restructuring Activities - Summ

Restructuring Activities - Summary of Severance Reserves and Facility Cost Reserves (Details) $ in Millions	6 Months Ended
	Mar. 31, 2019USD ($)
Restructuring Cost And Reserve [Line Items]
Beginning balance	$ 43
Restructuring reserve	12
Utilization (cash paid)	(23)
Ending balance	32
Severance Costs [Member]
Restructuring Cost And Reserve [Line Items]
Beginning balance	36
Restructuring reserve	4
Utilization (cash paid)	(18)
Ending balance	22
Facility Costs [Member]
Restructuring Cost And Reserve [Line Items]
Beginning balance	7
Restructuring reserve	8
Utilization (cash paid)	(5)
Ending balance	$ 10

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Instruments Subject to Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions		Mar. 31, 2019	Sep. 30, 2018
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Assets
Cash and cash equivalents		$ 164	$ 294
Restricted investments	[1]	326	342
Deferred compensation investments	[2]	166	165
Investment of captive insurance company		4	3
Foreign currency derivatives		3	11
Total assets at fair value		663	815
Liabilities
Foreign currency derivatives		3	3
Estimate of Fair Value, Fair Value Disclosure [Member]
Assets
Cash and cash equivalents		164	294
Restricted investments	[1]	326	342
Deferred compensation investments	[2]	166	165
Investment of captive insurance company		4	3
Foreign currency derivatives		3	11
Total assets at fair value		663	815
Liabilities
Foreign currency derivatives		3	3
Fair Value, Inputs, Level 1 [Member]
Assets
Cash and cash equivalents		164	294
Restricted investments	[1]	326	342
Deferred compensation investments	[2]	0	0
Investment of captive insurance company		4	3
Foreign currency derivatives		0	0
Total assets at fair value		494	639
Liabilities
Foreign currency derivatives		0	0
Fair Value, Inputs, Level 2 [Member]
Assets
Cash and cash equivalents		0	0
Restricted investments	[1]	0	0
Deferred compensation investments	[2]	166	165
Investment of captive insurance company		0	0
Foreign currency derivatives		3	11
Total assets at fair value		169	176
Liabilities
Foreign currency derivatives		3	3
Fair Value, Inputs, Level 3 [Member]
Assets
Cash and cash equivalents		0	0
Restricted investments	[1]	0	0
Deferred compensation investments	[2]	0	0
Investment of captive insurance company		0	0
Foreign currency derivatives		0	0
Total assets at fair value		0	0
Liabilities
Foreign currency derivatives		$ 0	$ 0
[1]	Included in restricted investments is $30 million classified in the other current assets caption on the Condensed Consolidated Balance Sheets.
[2]	Included in other noncurrent assets in the Condensed Consolidated Balance Sheets.

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Financial Instruments Subject to Recurring Fair Value Measurements (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Restricted Investments, Current	$ 30	$ 30

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Investment Portfolio (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended			12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019		Mar. 31, 2018	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Original cost		$ 335		$ 335			$ 335
Accumulated adjustments, net		(47)		(47)			(38)
Adjusted cost	[1]	288		288			297
Investment income		2	$ 2	5	[2]	$ 4	8	[2]
Net unrealized gain	[3]			25			54
Realized gains	[3]			26			6
Settlement funds				2			10
Disbursements		(12)	$ (12)	(20)		$ (17)	(33)
Fair value		$ 326		$ 326			$ 342
[1]	The accumulated adjustments include investment income, realized gains, disbursements and settlements recorded in previous periods.
[2]	Investment income for the demand deposit includes interest income as well as dividend income transferred from the equity and corporate bond mutual funds.
[3]	Presented under the original cost method.

Fair Value Measurements - Sum_4

Fair Value Measurements - Summary of Restricted Investment Securities Portfolio (Details) - USD ($) $ in Millions		Mar. 31, 2019	Sep. 30, 2018
Schedule of Available-for-sale Securities [Line Items]
Adjusted cost	[1]	$ 288	$ 297
Total, fair value		326	342
Corporate bond mutual fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted cost		66	120
Unrealized gain		0	0
Unrealized loss		0	(5)
Total, fair value		66	115
Equity mutual fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted cost		71	148
Unrealized gain		25	59
Unrealized loss		0	0
Total, fair value		96	207
Demand Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Demand deposit		164	20
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Adjusted cost		301	288
Unrealized gain		25	59
Unrealized loss		0	(5)
Total, fair value		$ 326	$ 342
[1]	The accumulated adjustments include investment income, realized gains, disbursements and settlements recorded in previous periods.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Restricted Investment [Abstract]
Unrealized gains on equity securities	[1]	$ 27	$ (8)	$ (3)	$ 2
Fair Value Disclosures [Abstract]
Gains (loss) related to deferred compensation investments		5	$ 0	1	$ 4
Other financial instruments [Abstract]
Long-term Debt, Carrying Value		2,300		2,300		$ 2,307
Long-term Debt, Fair Value		$ 2,401		$ 2,401		2,372
Accounting Standards Update 2016-01 | Reclassified from AOCI to Retained Earnings [Member]
Restricted Investment [Abstract]
Unrealized gains on equity securities						54
Deferred income taxes						$ 20
[1]	Ashland determined that all unrealized gains and losses were related to equity securities with readily determinable fair values. Due to the new accounting guidance adopted in the first quarter of fiscal year 2019, the net unrealized losses during the three and six months ended March 31, 2019 were recorded within the net interest and other expense (income) caption in the Statements of Consolidated Comprehensive Income (Loss). In 2018 these net unrealized gains (losses) were in AOCI.

Fair Value Measurements - Sum_5

Fair Value Measurements - Summary of Investment Income, Net Unrealized Gains and Losses, Realized Gains and Disbursements Related to Investments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended			12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019		Mar. 31, 2018	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Investment income		$ 2	$ 2	$ 5	[1]	$ 4	$ 8	[1]
Net unrealized gains (losses)	[2]	27	(8)	(3)		2
Realized gains	[3]	0	3	0		4
Disbursements		$ (12)	$ (12)	$ (20)		$ (17)	$ (33)
[1]	Investment income for the demand deposit includes interest income as well as dividend income transferred from the equity and corporate bond mutual funds.
[2]	Ashland determined that all unrealized gains and losses were related to equity securities with readily determinable fair values. Due to the new accounting guidance adopted in the first quarter of fiscal year 2019, the net unrealized losses during the three and six months ended March 31, 2019 were recorded within the net interest and other expense (income) caption in the Statements of Consolidated Comprehensive Income (Loss). In 2018 these net unrealized gains (losses) were in AOCI.
[3]	Relates only to the three and six months ended March 31, 2018 prior to the adoption of the new accounting guidance for equity securities.

Fair Value Measurements - Sum_6

Fair Value Measurements - Summary of Net Gains and Losses on Foreign Currency Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative gains (losses)	$ 3	$ (16)	$ 4	$ (27)

Fair Value Measurements - Sum_7

Fair Value Measurements - Summary of Fair Values of Outstanding Foreign Currency Derivatives (Details) - Foreign Exchange Contract [Member] - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Accounts Receivable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative assets	$ 3	$ 11
Notional contract values	319	1,209
Accrued Expenses and Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional contract values	378	755
Foreign currency derivative liabilities	$ 3	$ 3

Inventories - Summary of Invent

Inventories - Summary of Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Inventory Disclosure [Abstract]
Finished products	$ 378	$ 381
Raw materials, supplies and work in process	221	215
Inventory, Net	$ 599	$ 596

Goodwill and Other Intangible_2

Goodwill and Other Intangibles - Additional Information (Details) $ in Millions	Jul. 01, 2018ReportableSegment	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2019USD ($)ReportableSegmentReportingUnit	Mar. 31, 2018USD ($)
Finite Lived Intangible Assets [Line Items]
Number of reportable segments | ReportableSegment	3			2
Number of remaining reporting units | ReportingUnit				2
Finite-Lived Intangible Assets, Net [Abstract]
Amortization expense recognized on intangible assets		$ 21	$ 23	$ 43	$ 46
Expected future amortization expense [Abstract]
2019 (includes six months actual and six months estimated)		86		86
2020		86		86
2021		85		85
2022		85		85
2023		$ 84		$ 84
Minimum [Member] | Trademarks and Trade Names [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				3 years
Minimum [Member] | Intellectual Property [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				5 years
Minimum [Member] | Customer and supplier relationships [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				3 years
Maximum [Member] | Trademarks and Trade Names [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				25 years
Maximum [Member] | Intellectual Property [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				25 years
Maximum [Member] | Customer and supplier relationships [Member]
Intangible Assets, Net [Abstract]
Useful life (in years)				24 years

Goodwill and Other Intangible_3

Goodwill and Other Intangibles - Summary of Goodwill by Reportable Segment (Details) $ in Millions	6 Months Ended
	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 2,304
Acquisitions	0
Currency translation	(25)
Balance at end of period	2,279
Specialty Ingredients [Member]
Goodwill [Roll Forward]
Balance at beginning of period	2,304
Acquisitions	0
Currency translation	(25)
Balance at end of period	2,279
Intermediates and Solvents [Member]
Goodwill [Roll Forward]
Balance at beginning of period	0	[1]
Acquisitions	0	[1]
Currency translation	0	[1]
Balance at end of period	$ 0	[1]
[1]	As of March 31, 2019 and September 30, 2018, there was accumulated impairment of $90 million related to the Intermediates and Solvents reportable segment.

Goodwill and Other Intangible_4

Goodwill and Other Intangibles - Summary of Goodwill by Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Intermediates and Solvents [Member]
Goodwill [Line Items]
Accumulated impairment	$ 90	$ 90

Goodwill and Other Intangible_5

Goodwill and Other Intangibles - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,531	$ 1,546
Accumulated amortization	(674)	(639)
Net carrying amount	857	907
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Intangible Assets, Gross (Excluding Goodwill)	1,809	1,824
Intangibles	1,135	1,185
Trademarks and Trade Names [Member]
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Trademarks and trade names	278	278
Trademarks and Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	66	66
Accumulated amortization	(27)	(25)
Net carrying amount	39	41
Intellectual Property [Member]
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	715	721
Accumulated amortization	(370)	(350)
Net carrying amount	345	371
Customer and supplier relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	750	759
Accumulated amortization	(277)	(264)
Net carrying amount	$ 473	$ 495

Debt - Summary of Current and L

Debt - Summary of Current and Long-term Debt (Details) - USD ($) $ in Millions		Mar. 31, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Carrying value of debt		$ 2,300	$ 2,307
Other	[1]	7	5
Total debt		2,536	2,529
Short-term debt (includes current portion of long-term debt)		(261)	(254)
Long-term debt (less current portion)		2,275	2,275
Notes due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of debt		1,083	1,083
Term Loan B due 2024 [Member]
Debt Instrument [Line Items]
Carrying value of debt		590	593
Notes due 2043 [Member]
Debt Instrument [Line Items]
Carrying value of debt		376	376
Term Loan A due 2022 [Member]
Debt Instrument [Line Items]
Carrying value of debt		195	195
2017 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Carrying value of debt		25	25
Accounts Receivable Securitization [Member]
Debt Instrument [Line Items]
Carrying value of debt		207	195
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Carrying value of debt		$ 53	52
Medium-term Notes [Member]
Debt Instrument [Line Items]
Carrying value of debt			$ 5
[1]	Includes $19 million and $21 million of debt issuance cost discounts as of March 31, 2019 and September 30, 2018, respectively, in addition to a European short-term loan facility with an outstanding balance of $23 million at both March 31, 2019 and September 30, 2018.

Debt - Summary of Current and_2

Debt - Summary of Current and Long-term Debt (Parenthetical) (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense, Long-Term Debt	$ 19	$ 21
Short-term debt - Note H	$ 261	254
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Debt Instrument, Maturity Date	Jun. 30, 2029
Medium-term Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	9.40%
Debt Instrument, Maturity Date	Jan. 24, 2019
Notes due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.75%
Debt Instrument, Maturity Date	Aug. 15, 2022
Term Loan B due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	May 17, 2024
Debt Instrument, maturity year	2024
Notes due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.875%
Debt Instrument, Maturity Date	May 15, 2043
Term Loan A due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	May 17, 2022
Debt Instrument, maturity year	2022
European Facility [Member]
Debt Instrument [Line Items]
Short-term debt - Note H	$ 23	$ 23

Debt - Summary of Current and_3

Debt - Summary of Current and Long-term Debt - Additional Information (Details) $ in Millions	Mar. 31, 2019USD ($)
Scheduled aggregate debt maturities by fiscal year [Abstract]
2019	$ 3
2020	6
2021	14
2022	1,279
2023	$ 6

Debt - Financing Activity and C

Debt - Financing Activity and Covenants - Additional Information (Details)	6 Months Ended
	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 741,000,000
Covenant restrictions [Abstract]
Maximum consolidated leverage ratio	4.5
Calculated leverage ratio	3.5
Minimum required consolidated interest coverage ratio	3
Calculated consolidated interest coverage ratio	5.6
2017 Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 727,000,000
Line of credit facility outstanding principal amount	25,000,000
Letters of Credit Outstanding, Amount	48,000,000
Accounts Receivable Securitization [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 14,000,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Mar. 31, 2018
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				35.00%	21.00%
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount		$ 24
Increase (Decrease) in Deferred Income Taxes		2
One-time transition tax liability, unfavorable tax adjustment		22
Increase (Decrease) in Deferred Liabilities		$ 51
Minimum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 2				$ 2
Maximum [Member]
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 4				$ 4
Current Fiscal Year [Member]
Income Tax Contingency [Line Items]
Effective tax rate (in hundredths)	(2.00%)				2500.00%
Current Fiscal Year [Member] | Foreign Country [Member]
Income Tax Contingency [Line Items]
Income tax rate reconciliation, valuation allowances	$ (11)				$ 30
Prior Fiscal Year [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount			$ (16)
Effective tax rate (in hundredths)			5.00%			(44.00%)
Prior Fiscal Year [Member] | Foreign Country [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount			$ 5

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Unrecognized Tax Benefits (Details) $ in Millions	6 Months Ended
	Mar. 31, 2019USD ($)
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 164
Decreases related to positions taken on items from prior years	(3)
Increases related to positions taken in the current year	3
Lapse of statute of limitations	(2)
Balance at end of period	$ 162

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended
	Dec. 31, 2018	Mar. 31, 2019
Foreign Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual contributions to benefit plans in period		$ 3,000,000
Estimated future contributions in current fiscal year		3,000,000
Remeasurement due to curtailment gain	$ 18,000,000
United States Pension Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual contributions to benefit plans in period		$ 0

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of Components of Pension and Other Postretirement Benefit Costs for Continuing Operation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 2	$ 3	$ 4
Interest cost	2	2	5	5
Expected return on plan assets	(2)	(3)	(5)	(6)
Curtailment	0	0	(18)	0
Actuarial (gain) loss	0	0	0	0
Total net periodic benefit costs (income)	1	1	(15)	3
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	1
Interest cost	1	0	1	0
Expected return on plan assets	0	0	0	0
Curtailment	0	0	0	0
Actuarial (gain) loss	0	0	0	0
Total net periodic benefit costs (income)	$ 1	$ 0	$ 1	$ 1

Litigation, Claims and Contin_3

Litigation, Claims and Contingencies - Summary of Asbestos Claims Activity (Details) - Claim Claim in Thousands	6 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Ashland [Member]
Asbestos claims [Roll Forward]
Open claims - beginning of year	53	54	54	57	60
New claims filed	1	1	2	2	2
Claims settled	0	0	(1)	(1)	0
Claims dismissed	(1)	(2)	(2)	(4)	(5)
Open claims - end of period	53	53	53	54	57
Hercules [Member]
Asbestos claims [Roll Forward]
Open claims - beginning of year	13	12	12	15	20
New claims filed		1	2	1	1
Claims dismissed	(1)	(1)	(1)	(4)	(6)
Open claims - end of period	12	12	13	12	15

Litigation, Claims and Contin_4

Litigation, Claims and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended				12 Months Ended
	Jun. 30, 2018USD ($)	Mar. 31, 2019USD ($)WasteTreatmentorDisposalSiteFacilityServiceStationProperty		Mar. 31, 2018USD ($)		Sep. 30, 2018USD ($)		Sep. 30, 2017USD ($)		Sep. 30, 2016USD ($)		Sep. 30, 2015USD ($)
Environmental Remediation Costs Recognized [Abstract]
Number of waste treatment or disposal sites were company is identified as a potentially responsible party under the superfund or similar state laws | WasteTreatmentorDisposalSite		81
Number of current and former operating facilities subject to various environmental laws | Facility		116
Total number of service station properties subject to various environmental laws | ServiceStationProperty		1,225
Number of service stations being actively remediated | ServiceStationProperty		31
Accrual for environmental loss contingencies		$ 179		$ 164		$ 187		$ 163
Accrued environmental loss contingencies, noncurrent		139				147
Recorded third-party environmental recoveries receivable		12				12
Recorded third-party environmental recoveries, noncurrent		$ 11				11
Maximum reserve for remediation reserve related to any one site (in hundredths)		15.00%
Minimum [Member]
Asbestos litigation cost projection [Abstract]
Number of Years Included in Asbestos Assumption		40 years
Maximum [Member]
Asbestos litigation cost projection [Abstract]
Number of Years Included in Asbestos Assumption		50 years
Environmental Remediation Costs Recognized [Abstract]
Environmental exit costs, reasonably possible additional loss		$ 421
Ashland [Member]
Asbestos claims [Roll Forward]
Decrease in asbestos-related claims	$ 8	0		0		8		(36)		$ (37)
Total reserves for asbestos claims		366	[1]	402	[1]	380	[1]	419	[1]	415	[1]	$ 409
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable		136	[2]	149	[2]	140	[2]	155	[2]	151	[2]	150
Receivable adjustment	(5)	0		0		(5)		15		16
Asbestos litigation cost projection [Abstract]
Possible total future litigation defense and claim settlement costs		600
Total reserves for asbestos claims		366	[1]	402	[1]	380	[1]	419	[1]	415	[1]	409
Hercules [Member]
Asbestos claims [Roll Forward]
Decrease in asbestos-related claims	19	0		0		19		(16)		(25)
Total reserves for asbestos claims		272	[3]	311	[3]	282	[3]	323	[3]	321	[3]	311
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable		54		68		54		68		63		56
Receivable adjustment	$ (14)	0		0		(14)		5		7
Asbestos litigation cost projection [Abstract]
Possible total future litigation defense and claim settlement costs		450
Total reserves for asbestos claims		$ 272	[3]	$ 311	[3]	$ 282	[3]	$ 323	[3]	$ 321	[3]	$ 311
[1]	Includes $31 million and $30 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2019 and September 30, 2018, respectively.
[2]	Includes $15 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018
[3]	Included $20 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018.

Litigation, Claims and Contin_5

Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended				12 Months Ended
		Jun. 30, 2018		Mar. 31, 2019		Mar. 31, 2018		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2016
Ashland [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve - beginning of year		$ 402	[1]	$ 380	[1]	$ 419	[1]	$ 419	[1]	$ 415	[1]	$ 409
Reserve adjustment		(8)		0		0		(8)		36		37
Amounts paid				(14)		(17)		(31)		(32)		(31)
Asbestos reserve - end of period	[1]			366		402		380		419		415
Hercules [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve - beginning of year		311	[2]	282	[2]	323	[2]	323	[2]	321	[2]	311
Reserve adjustment		$ (19)		0		0		(19)		16		25
Amounts paid				(10)		(12)		(22)		(14)		(15)
Asbestos reserve - end of period	[2]			$ 272		$ 311		$ 282		$ 323		$ 321
[1]	Includes $31 million and $30 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2019 and September 30, 2018, respectively.
[2]	Included $20 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018.

Litigation, Claims and Contin_6

Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2019		Sep. 30, 2018		Mar. 31, 2018		Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2015
Ashland [Member]
Asbestos claims [Roll Forward]
Asbestos reserve	$ 366	[1]	$ 380	[1]	$ 402	[1]	$ 419	[1]	$ 415	[1]	$ 409
Ashland [Member] | Other Current Liabilities [Member]
Asbestos claims [Roll Forward]
Asbestos reserve	31		30
Hercules [Member]
Asbestos claims [Roll Forward]
Asbestos reserve	272	[2]	282	[2]	$ 311	[2]	$ 323	[2]	$ 321	[2]	$ 311
Hercules [Member] | Other Current Liabilities [Member]
Asbestos claims [Roll Forward]
Asbestos reserve	$ 20		$ 20
[1]	Includes $31 million and $30 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2019 and September 30, 2018, respectively.
[2]	Included $20 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018.

Litigation, Claims and Contin_7

Litigation, Claims and Contingencies - Summary of Progression of Insurance Receivable (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended				12 Months Ended
		Mar. 31, 2019	Jun. 30, 2018		Mar. 31, 2018	Mar. 31, 2019		Mar. 31, 2018		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2016
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance settlement	[1]	$ 0			$ 1	$ 1		$ 1
Ashland [Member]
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable - beginning of year			$ 149	[2]		140	[2]	155	[2]	$ 155	[2]	$ 151	[2]	$ 150
Receivable adjustment			(5)			0		0		(5)		15		16
Insurance settlement						0		0		0		(5)		(4)
Amounts collected						(4)		(6)		(10)		(6)		(11)
Insurance receivable - end of period	[2]	136			149	136		149		140		155		151
Hercules [Member]
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable - beginning of year			68			54		68		68		63		56
Receivable adjustment			$ (14)			0		0		(14)		5		7
Insurance receivable - end of period		$ 54			$ 68	$ 54		$ 68		$ 54		$ 68		$ 63
[1]	Activity of $0 denotes value less than $1 million.
[2]	Includes $15 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018

Litigation, Claims and Contin_8

Litigation, Claims and Contingencies - Summary of Progression of Insurance Receivable (Parenthetical) (Details) - Ashland [Member] - USD ($) $ in Millions	Mar. 31, 2019		Sep. 30, 2018		Mar. 31, 2018	[1]	Sep. 30, 2017	[1]	Sep. 30, 2016	[1]	Sep. 30, 2015
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable	$ 136	[1]	$ 140	[1]	$ 149		$ 155		$ 151		$ 150
Accounts Receivable [Member]
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable	$ 15		$ 15
[1]	Includes $15 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of both March 31, 2019 and September 30, 2018

Litigation, Claims and Contin_9

Litigation, Claims and Contingencies - Summary of Reconciliation of Changes in Environmental Remediation Reserves (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Environmental Remediation Obligations [Abstract]
Reserve - beginning of period	$ 187	$ 163
Disbursements	(15)	(16)
Revised obligation estimates and accretion	7	17
Reserve - end of period	$ 179	$ 164

Litigation, Claims and Conti_10

Litigation, Claims and Contingencies - Summary of Components of Environmental Remediation Expense Included within Selling, General and Administrative Expense (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Environmental Expense And Liabilities [Abstract]
Environmental expense		$ 3	$ 4	$ 6	$ 16
Accretion		1	0	1	1
Legal expense		2	2	3	3
Total expense		6	6	10	20
Insurance receivable	[1]	0	(1)	(1)	(1)
Total expense, net of receivable activity	[2]	$ 6	$ 5	$ 9	$ 19
[1]	Activity of $0 denotes value less than $1 million.
[2]	Net expense of $1 million and $2 million for the three and six months ended March 31, 2019, and $1 million for both the three and six months ended March 31, 2018, relates to divested businesses which qualified for treatment as discontinued operations for which certain environmental liabilities were retained by Ashland. These amounts are classified within the income from discontinued operations caption of the Statements of Consolidated Comprehensive Income (loss).

Litigation, Claims and Conti_11

Litigation, Claims and Contingencies - Summary of Components of Environmental Remediation Expense Included within Selling, General and Administrative Expense (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Environmental Expense And Liabilities [Abstract]
Net expense relates to divested businesses	$ 1	$ 1	$ 2	$ 1

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - shares shares in Millions	6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Antidilutive securities excluded from calculation of earnings per share	1	0.7

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Numerator
Numerator for basic and diluted EPS - Income (loss) from continuing operations		$ 45	$ 42	$ (26)	$ 10
Denominator
Denominator for basic EPS - Weighted-average common shares outstanding		63	63	63	63
Share based awards convertible to common shares	[1]	1	1	0	1
Denominator for diluted EPS - Adjusted weighted-average shares and assumed conversions		64	64	63	64
PER SHARE DATA
Basic		$ 0.72	$ 0.66	$ (0.41)	$ 0.15
Diluted		$ 0.71	$ 0.65	$ (0.41)	$ 0.15
[1]	As a result of the loss from continuing operations attributable to Ashland during the six months ended March 31, 2019, the effect of the share-based awards convertible to common shares would be antidilutive. In accordance with U.S. GAAP, these shares have been excluded from the diluted EPS calculation.

Equity Items - Additional Infor

Equity Items - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Accelerated Share Repurchases [Line Items]
Common Stock, Dividends, Per Share, Paid	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.225	$ 0.225
Common Stock, Dividends Declared, Paid	$ 16,000,000	$ 16,000,000	$ 16,000,000	$ 16,000,000
Percentage of increase in cash dividend					11.00%	11.00%
2018 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount					$ 1,000,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,000,000,000

Equity Items - Components of Ac

Equity Items - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Unrealized translation gain (loss), before tax		$ (9)	$ 55	$ (40)	$ 58
Unrealized translation gain (loss), tax		0	0	0	0
Unrealized translation gain (loss), net of tax		(9)	55	(40)	58
Adjustment of unrecognized prior service cost (credit), before tax		0	0	(7)	0
Adjustment of unrecognized prior service cost (credit), tax		0	0	1	0
Adjustment of unrecognized prior service cost (credit), net of tax		0	0	(6)	0
Unrealized gain on investment, before taxes	[1]	0	(5)	0	6
Unrealized gain on investment, tax	[1]	0	1	0	(1)
Unrealized gain on investment, net of tax	[1]	0	(4)	0	5
Reclassification adjustment for gains included in net income, before tax		0	(3)	0	(4)
Reclassification adjustment for gains included in net income, tax		0	1	0	1
Reclassification adjustment for gains included in net income, net of tax		0	(2)	0	(3)
Total other comprehensive income (loss), before tax		(9)	47	(47)	60
Total other comprehensive income (loss), tax		0	2	1	0
Other comprehensive income (loss)		$ (9)	$ 49	$ (46)	$ 60
[1]	Due to the adoption of new accounting guidance in fiscal 2019, unrealized gains and losses on Ashland’s equity securities are now recognized in net income rather than AOCI. See Notes A and E for more information

Equity Items - Summary of Recon

Equity Items - Summary of Reconciliation of Changes in Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Ending Balance		$ 3,362	$ 3,511	$ 3,362	$ 3,511
Cash dividends declared per common share		$ 0.25	$ 0.225	$ 0.50	$ 0.45
Common Stock and Paid In Capital [Member]
Beginning Balance		$ 948	$ 932	$ 947	$ 932
Common shares issued under stock incentive and other plans	[1]	5	4	6	4
Ending Balance		953	936	953	936
Retained earnings [Member]
Beginning Balance		2,719	2,678	2,750	2,696
Adoption of new accounting pronouncements	[2]	1		34
Net income (loss)		76	73	28	69
Regular dividends		(16)	(14)	(32)	(28)
Ending Balance		2,780	2,737	2,780	2,737
Accumulated other comprehensive income (loss) [Member]
Beginning Balance		(362)	(211)	(291)	(222)
Adoption of new accounting pronouncements	[2]			(34)
Unrealized translation gain (loss)		(9)	55	(40)	58
Pension and postretirement obligation adjustment				(6)
Net change in investment securities			(6)		2
Ending Balance		$ (371)	$ (162)	$ (371)	$ (162)
[1]	Common share issued were 93,738 and 154,421 for the three months ended March 31, 2019 and 2018 and 234,352 and 265,821 for the six months ended March 31, 2019 and 2018.
[2]	Represents the cumulative-effect adjustment related to the adoption of the new guidance related to the accounting for equity securities and tax effects of intercompany transfers during fiscal 2019. See Note A for more information.

Equity Items - Summary of Rec_2

Equity Items - Summary of Reconciliation of Changes in Stockholders' Equity (Parenthetical) (Details) - shares	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Common shares issued	93,738	154,421	234,352	265,821

Stock Incentive Plans - Compone

Stock Incentive Plans - Components of Stock-Based Compensation Expense Included in Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2019	[1]	Mar. 31, 2018	[2]	Mar. 31, 2019	[1]	Mar. 31, 2018	[2]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 10		$ 9		$ 16		$ 20
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2		2		4		3
Nonvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	6		5		10		11
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2		$ 2		$ 2		$ 6
[1]	Included $2 million and $3 million of expense related to cash-settled nonvested restricted stock awards during the three and six months ended March 31, 2019 and $2 million of expense related to cash-settled performance units during the three ended March 31, 2019.
[2]	Included $2 million and $4 million of expense related to cash-settled nonvested restricted stock awards and $1 million and $3 million of expense related to cash-settled performance units during the three and six months ended March 31, 2018, respectively.

Stock Incentive Plans - Compo_2

Stock Incentive Plans - Components of Stock-Based Compensation Expense Included in Continuing Operations (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2019		Mar. 31, 2018		Mar. 31, 2019		Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 10	[1]	$ 9	[2]	$ 16	[1]	$ 20	[2]
Cash-settled Nonvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2		2		$ 3		4
Cash-settled Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2		$ 1				$ 3
[1]	Included $2 million and $3 million of expense related to cash-settled nonvested restricted stock awards during the three and six months ended March 31, 2019 and $2 million of expense related to cash-settled performance units during the three ended March 31, 2019.
[2]	Included $2 million and $4 million of expense related to cash-settled nonvested restricted stock awards and $1 million and $3 million of expense related to cash-settled performance units during the three and six months ended March 31, 2018, respectively.

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2019		Mar. 31, 2018		Mar. 31, 2019		Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 10	[1]	$ 9	[2]	$ 16	[1]	$ 20	[2]
Number of common shares for each converted performance share	1				1
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unexercised SARs generally lapse expiration period					10 years
Grants of share-based payment awards in period					300,000		470,000
Total unrecognized compensation costs	$ 10				$ 10
Model to fair value share-based payment awards					Black-Scholes option-pricing model
Unrecognized cost expected to be recognized over a weighted-average period (in years)					2 years 1 month 6 days
Stock-based compensation	$ 2	[1]	$ 2	[2]	$ 4	[1]	$ 3	[2]
Stock Appreciation Rights (SARs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					1 year
Stock Appreciation Rights (SARs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					3 years
Nonvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants of share-based payment awards in period	13,000		2,000		94,000		144,000
Total unrecognized compensation costs			$ 11				$ 11
Unrecognized cost expected to be recognized over a weighted-average period (in years)					1 year 10 months 24 days
Stock-based compensation	$ 6	[1]	5	[2]	$ 10	[1]	11	[2]
Nonvested Stock Awards [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					1 year
Nonvested Stock Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					5 years
Cash-settled Nonvested Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	200,000				200,000
Stock-based compensation	$ 2		2		$ 3		4
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs	$ 1				$ 1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	30,000				30,000
Stock-based compensation	$ 1		$ 2		$ 1		$ 3
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of share-based payment award					3 years
Grants of share-based payment awards in period	0		0		78,000		101,000
Total unrecognized compensation costs	$ 13				$ 13
Unrecognized cost expected to be recognized over a weighted-average period (in years)					2 years
Stock-based compensation	$ 2	[1]	$ 2	[2]	$ 2	[1]	$ 6	[2]
[1]	Included $2 million and $3 million of expense related to cash-settled nonvested restricted stock awards during the three and six months ended March 31, 2019 and $2 million of expense related to cash-settled performance units during the three ended March 31, 2019.
[2]	Included $2 million and $4 million of expense related to cash-settled nonvested restricted stock awards and $1 million and $3 million of expense related to cash-settled performance units during the three and six months ended March 31, 2018, respectively.

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
Revenue From Contracts With Customers [Line Items]
Maximum cash collection period from customer	60 days
Cost incurred to obtain contract with customer amortization period of practical expedients	true
Trade Receivable [Member]
Revenue From Contracts With Customers [Line Items]
Trade receivables	$ 491	$ 482

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Sales	$ 667	$ 672	$ 1,243	$ 1,253
Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	637	646	1,190	1,196
Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	30	26	53	57
North America [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	247	258	466	481
North America [Member] | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	15	13	26	27
Europe [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	220	222	390	389
Europe [Member] | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	6	6	11	13
Asia Pacific | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	115	111	231	218
Asia Pacific | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	7	6	13	14
Latin America & Other [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	55	55	103	108
Latin America & Other [Member] | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	2	1	3	3
Cellulosics [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	224	215	413	393
Poly-vinyl pyrrolidones [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	110	115	205	210
Adhesives [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	89	90	171	169
Actives [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	43	42	80	80
Vinyl Ethers [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	31	38	55	66
Pharmachem [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	64	63	123	121
Derivatives [Member] | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	25	21	45	48
Butanediol [Member] | Intermediates and Solvents [Member]
Disaggregation Of Revenue [Line Items]
Sales	5	5	8	9
Other [Member] | Specialty Ingredients [Member]
Disaggregation Of Revenue [Line Items]
Sales	$ 76	$ 83	$ 143	$ 157

Reportable Segment Informatio_2

Reportable Segment Information - Additional Information (Details) - ReportableSegment	Jul. 01, 2018	Mar. 31, 2019
Segment Reporting [Abstract]
Number of reportable segments	3	2

Reportable Segment Informatio_3

Reportable Segment Information - Summary of Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Sales	$ 667	$ 672	$ 1,243	$ 1,253
Operating Income (Loss)	44	63	37	67
Specialty Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	637	646	1,190	1,196
Operating Income (Loss)	70	89	96	131
Intermediates and Solvents [Member]
Segment Reporting Information [Line Items]
Sales	30	26	53	57
Operating Income (Loss)	5	3	5	6
Unallocated and other [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (31)	$ (29)	$ (64)	$ (70)

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - 2018 Stock Repurchase Program [Member] - USD ($)	Apr. 30, 2019	Mar. 31, 2018
Subsequent Event [Line Items]
Stock Repurchase Program, Authorized Amount		$ 1,000,000,000
Subsequent Events [Member]
Subsequent Event [Line Items]
Stock repurchase, amount	$ 200,000,000