Note 13. Retirement Plans (Details) - USD ($)	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	$ 1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	3,000,000	$ 1,000,000
Defined Contribution Plan, Cost Recognized	58,000,000
Pension and Other Postretirement Benefit Contributions	38,000,000	35,000,000	$ 25,000,000
Benefit Plan Expense Allocated from Former Parent (DB & DC)	0	21,000,000	32,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	472,000,000	519,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	450,000,000	495,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets	342,000,000	331,000,000
Voluntary contributions to defined benefit plans.	2,000,000
Prescription Drug Benefit, Effect of Subsidy on Net Periodic Postretirement Benefit Cost	0
Defined Benefit Plan, Amortization of Gains (Losses)	45,000,000	(110,000,000)	(6,000,000)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	577,000,000	613,000,000
Defined Benefit Plan, Fair Value of Plan Assets	491,000,000	457,000,000	421,000,000
Net Asset Value Excluded from Fair Value Hierarchy	107,000,000	97,000,000
Pension and Other Postretirement Benefit Contributions	37,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	26,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	27,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	28,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	27,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	33,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	176,000,000
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	13,000,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	2,000,000	2,000,000
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	0
Defined Benefit Plan, Benefit Obligation	600,000,000	637,000,000	527,000,000
Defined Benefit Plan, Service Cost	8,000,000	8,000,000	10,000,000
Defined Benefit Plan, Interest Cost	12,000,000	16,000,000	19,000,000
Defined Benefit Plan, Contributions by Plan Participants	0	0
Defined Benefit Plan, Actuarial Gain (Loss)	(51,000,000)	132,000,000
Defined Benefit Plan, Benefits and Settlements Paid Obligation	29,000,000	30,000,000
Defined Benefit Plan, Other Changes	0	14,000,000
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	23,000,000	(30,000,000)
Defined Benefit Plan, Actual Return on Plan Assets	9,000,000	44,000,000
Defined Benefit Plan, Contributions by Employer and Employee	37,000,000	35,000,000
Defined Benefit Plan, Benefits and Settlements Paid Assets	29,000,000	30,000,000
Defined Benefit Plan, Other Changes Assets	0	16,000,000
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets	17,000,000	(29,000,000)
Defined Benefit Plan, Funded Status of Plan	(109,000,000)	(180,000,000)
Defined Benefit Plan, Assets for Plan Benefits	22,000,000	8,000,000
Pension and Other Postretirement Defined Benefit Plans, Liabilities	131,000,000	188,000,000
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(109,000,000)	(180,000,000)
Defined Benefit Plan, Expected Return on Plan Assets	(17,000,000)	(22,000,000)	(21,000,000)
Defined Benefit Plan, Amortization of Gains (Losses)	(43,000,000)	109,000,000	6,000,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	1,000,000	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ (40,000,000)	$ 112,000,000	$ 14,000,000
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.25%	3.80%	4.35%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.50%	3.25%
Defined Benefit Plan, Accumulated Benefit Obligation	$ 0	$ 0
Defined Benefit Plan, Fair Value of Plan Assets	15,000,000	12,000,000	$ 13,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
Pension and Other Postretirement Benefit Contributions	2,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	1,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	1,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	1,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	1,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	1,000,000
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	7,000,000
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	0	0
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	0
Defined Benefit Plan, Benefit Obligation	16,000,000	16,000,000	15,000,000
Defined Benefit Plan, Service Cost	0	0	1,000,000
Defined Benefit Plan, Interest Cost	1,000,000	0	1,000,000
Defined Benefit Plan, Contributions by Plan Participants	1,000,000	1,000,000
Defined Benefit Plan, Actuarial Gain (Loss)	0	2,000,000
Defined Benefit Plan, Benefits and Settlements Paid Obligation	1,000,000	2,000,000
Defined Benefit Plan, Other Changes	(1,000,000)	0
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	0	0
Defined Benefit Plan, Actual Return on Plan Assets	2,000,000	1,000,000
Defined Benefit Plan, Contributions by Employer and Employee	2,000,000	1,000,000
Defined Benefit Plan, Benefits and Settlements Paid Assets	1,000,000	2,000,000
Defined Benefit Plan, Other Changes Assets	0	(1,000,000)
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets	0	0
Defined Benefit Plan, Funded Status of Plan	(1,000,000)	(4,000,000)
Defined Benefit Plan, Assets for Plan Benefits	0	0
Pension and Other Postretirement Defined Benefit Plans, Liabilities	1,000,000	4,000,000
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(1,000,000)	(4,000,000)
Defined Benefit Plan, Expected Return on Plan Assets	0	0	(1,000,000)
Defined Benefit Plan, Amortization of Gains (Losses)	(2,000,000)	1,000,000	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ (1,000,000)	$ 1,000,000	$ 1,000,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.35%	3.80%	4.00%
Cash [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 10,000,000	$ 13,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
Domestic Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	23,000,000	39,000,000
Net Asset Value Excluded from Fair Value Hierarchy	19,000,000	19,000,000
Domestic Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,000,000	3,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
International Developed Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	74,000,000	45,000,000
Net Asset Value Excluded from Fair Value Hierarchy	22,000,000	19,000,000
International Developed Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,000,000	1,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
International Emerging Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	10,000,000	7,000,000
Net Asset Value Excluded from Fair Value Hierarchy	4,000,000	4,000,000
International Emerging Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Net Asset Value Excluded from Fair Value Hierarchy		0
Government Debt Securities (US & Foreign) [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	195,000,000	172,000,000
Net Asset Value Excluded from Fair Value Hierarchy	32,000,000	23,000,000
Government Debt Securities (US & Foreign) [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,000,000	1,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
Corporate Debt Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	80,000,000	90,000,000
Net Asset Value Excluded from Fair Value Hierarchy	15,000,000	15,000,000
Corporate Debt Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,000,000	4,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
Commodities Investment [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Net Asset Value Excluded from Fair Value Hierarchy		0
Hedge Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	73,000,000	65,000,000
Net Asset Value Excluded from Fair Value Hierarchy	0	0
Real Estate Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,000,000	26,000,000
Net Asset Value Excluded from Fair Value Hierarchy	15,000,000	17,000,000
Real Estate Funds [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Net Asset Value Excluded from Fair Value Hierarchy		0
Fair Value, Inputs, Level 1 [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	200,000,000	230,000,000
Fair Value, Inputs, Level 1 [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,000,000	12,000,000
Fair Value, Inputs, Level 1 [Member] \| Cash [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	10,000,000	13,000,000
Fair Value, Inputs, Level 1 [Member] \| Domestic Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,000,000	20,000,000
Fair Value, Inputs, Level 1 [Member] \| Domestic Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,000,000	3,000,000
Fair Value, Inputs, Level 1 [Member] \| International Developed Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	52,000,000	26,000,000
Fair Value, Inputs, Level 1 [Member] \| International Developed Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5,000,000	1,000,000
Fair Value, Inputs, Level 1 [Member] \| International Emerging Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6,000,000	3,000,000
Fair Value, Inputs, Level 1 [Member] \| International Emerging Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Fair Value, Inputs, Level 1 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	76,000,000	98,000,000
Fair Value, Inputs, Level 1 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,000,000	1,000,000
Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	52,000,000	70,000,000
Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,000,000	4,000,000
Fair Value, Inputs, Level 1 [Member] \| Commodities Investment [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Fair Value, Inputs, Level 1 [Member] \| Hedge Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] \| Real Estate Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] \| Real Estate Funds [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,000,000
Fair Value, Inputs, Level 2 [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	173,000,000	121,000,000
Fair Value, Inputs, Level 2 [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Cash [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Domestic Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Domestic Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| International Developed Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| International Developed Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| International Emerging Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| International Emerging Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fair Value, Inputs, Level 2 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	87,000,000	51,000,000
Fair Value, Inputs, Level 2 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	13,000,000	5,000,000
Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Commodities Investment [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fair Value, Inputs, Level 2 [Member] \| Hedge Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	73,000,000	65,000,000
Fair Value, Inputs, Level 2 [Member] \| Real Estate Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] \| Real Estate Funds [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fair Value, Inputs, Level 3 [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11,000,000	9,000,000
Fair Value, Inputs, Level 3 [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Cash [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Domestic Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Domestic Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| International Developed Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| International Developed Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| International Emerging Equity Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| International Emerging Equity Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fair Value, Inputs, Level 3 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Government Debt Securities (US & Foreign) [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Commodities Investment [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fair Value, Inputs, Level 3 [Member] \| Hedge Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] \| Real Estate Funds [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 11,000,000	9,000,000	$ 8,000,000
Fair Value, Inputs, Level 3 [Member] \| Real Estate Funds [Member] \| Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		$ 0
United States Pension Plan of US Entity [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	3.70%	4.40%	4.35%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.85%	3.70%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	5.50%	7.50%	7.50%
Non-US [Member] \| Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	2.10%	3.40%	3.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.60%	2.10%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.55%	4.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.80%	4.45%	5.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	4.00%	3.00%	3.00%

Benefit Plan Expense Allocated from Former Parent (define benefit and defined contribution plans)

No definition available.

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- Definition

Defined Benefit Plan, Benefits and Settlements Paid Assets

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Defined Benefit Plan, Benefits and Settlements Paid Obligation

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Defined Benefit Plan, Contributions by Employer and Employee

+ References

No definition available.

+ Details

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Namespace Prefix:	adnt_
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Defined Benefit Plan, Other Changes Assets

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Net Asset Value Excluded from Fair Value Hierarchy: Represents investments for which fair value is measured using net asset value (NAV) per share practical expedient, and excluded from the fair value hierarchy.

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Voluntary contributions to defined benefit plans.

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No definition available.

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For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The pretax total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

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- Definition

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

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The amount of gains or losses recognized in net periodic benefit cost.

+ References

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Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

+ References

No definition available.

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The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

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This represents the entire assets recognized in the balance sheet that are associated with the defined benefit plans.

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The interest rate used to adjust for the time value of money for the plan.

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Expected rate of compensation increases (for pay-related plans).

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The interest rate used to adjust for the time value of money.

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An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

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Expected rate of compensation increases (for pay-related plans).

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1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

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The amount of contributions made by plan participants. This item represents a periodic increase to the plan obligation and an increase to plan assets.

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Amount of benefits from a defined benefit plan expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

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Amount of gain (loss) from foreign currency exchange rate changes for benefit obligation for plans of a foreign operation whose functional currency is not the reporting currency.

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The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency.

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The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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Changes in the defined benefit obligation, not otherwise separately disclosed in the financial statements.

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No definition available.

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If aggregate disclosures are presented, the aggregate pension accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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Amount of net gain (loss) recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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No definition available.

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Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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The amount of the cost recognized during the period for defined contribution plans.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and its non-pension postretirement benefit plans.

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This represents the entire liability recognized in the balance sheet that is associated with the defined benefit plans.

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Amount of the effect of the government subsidy for prescription drug benefits on the measurement of net periodic postretirement benefit cost. That effect includes (1) any amortization of the actuarial experience gain, (2) the reduction in current period service cost due to the subsidy, and (3) the resulting reduction in interest cost on the accumulated postretirement benefit obligation as a result of the subsidy.

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