Impairment of Long-Lived Assets	12 Months Ended
Impairment of Long-Lived Assets	Sep. 30, 2020
Restructuring and Related Activities [Abstract]
Impairment of Long-Lived Assets	16. Impairment of Long-Lived Assets Adient reviews long-lived assets, including property, plant and equipment and other intangible assets with definite lives, for impairment whenever events or changes in circumstances indicate that the asset's carrying amount may not be recoverable. Adient conducts its long-lived asset impairment analyses in accordance with ASC 360, "Impairment or Disposal of Long-Lived Assets." ASC 360 requires Adient to group assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities and evaluate the asset group against the sum of the undiscounted future cash flows. If the undiscounted cash flows do not indicate the carrying amount of the asset is recoverable, an impairment charge is measured as the amount by which the carrying amount of the asset group exceeds its fair value based on discounted cash flow analysis or appraisals. During the fourth quarter of fiscal 2020, a pre-tax non-cash impairment of $21 million was recorded on certain assets held for sale (of which $12 million related to America’s assets and $9 million related to China’s assets), and $5 million was recorded in the Asia segment related to long-lived assets within a separate China entity due to an overall decline in the forecasted operations within that business. During the third quarter of fiscal 2020, a pre-tax non-cash impairment of $27 million was recorded in the Asia segment related to customer relationship intangible assets of $24 million and other long-lived assets of $3 million within the Futuris China business due to an overall decline in forecasted operations within that business. All of the fiscal 2020 impairment charges are recorded within restructuring and impairment costs on the consolidated statement of income (loss). Refer to Note 3, “Acquisitions and Divestitures” of the notes to the consolidated financial statements for additional information on assets held for sale. Refer to Note 6, "Goodwill and Other Intangible Assets," of the notes to the consolidated financial statements for additional information on impairment of customer relationship intangible assets. During the fourth quarter of fiscal 2019, Adient recorded impairment on certain assets held for sale resulting in an impairment charge of $12 million which was recorded within restructuring and impairment costs on the consolidated statement of income (loss). In the second quarter of fiscal 2019, Adient concluded it had triggering events requiring assessment of impairment for certain of its long-lived assets in the seat structure and mechanism operations due to declines in actual and forecasted performance that worsened during the second quarter of fiscal 2019 as compared to originally forecasted results. As a result, Adient reviewed the long-lived assets for impairment and recorded a $66 million non-cash pre-tax impairment charge within restructuring and impairment costs on the consolidated statements of income (loss). The impairment charge related to long-lived assets in North America and Europe asset groups as of March 31, 2019 in support of current programs. Of the $66 million impairment charge, $62 million related to fixed assets, and $4 million related to customer relationship intangible assets. The impairment was measured under a market approach utilizing appraisal techniques to determine fair values of the impaired assets. This method is consistent with methods Adient employed in prior periods to value other long-lived assets. The inputs utilized in the analysis are classified as Level 3 inputs within the fair value hierarchy as defined in ASC 820, "Fair value measurement" and primarily consist of estimated salable values and third party appraisal techniques such as market comparables. To the extent that the profitability on current or future programs decline as compared to forecasted profitability or if adverse changes occur to key assumptions or other fair value measurement inputs, further impairment of long-lived assets could occur in the future. During the first quarter of fiscal 2019, impairments of $6 million were recorded related to assets held for sale. In the fourth quarter of fiscal 2018, Adient concluded it had triggering events requiring assessment of impairment for certain of its long-lived assets in the seat structure and mechanism operations due to the significant performance issues that persisted in fiscal 2018 and the resulting actions to turn around such operations identified during the fiscal 2019 planning process. As a result, Adient reviewed the long-lived assets for impairment and recorded a $787 million non-cash pre-tax impairment charge within restructuring and impairment costs on the consolidated statements of income (loss). The impairment charge related to long-lived assets in North America and Europe asset groups as of September 30, 2018 in support of current programs. Of the $787 million impairment charge, $768 million relates to fixed assets and $19 million relates to customer relationship intangible asset. The impairment was measured, depending on the asset, either under an income approach utilizing forecasted discounted cash flows or a market approach utilizing appraisal techniques to determine fair values of the impaired assets. These methods are consistent with the methods Adient employed in prior periods to value other long-lived assets. The inputs utilized in the analyses are classified as Level 3 inputs within the fair value hierarchy as defined in ASC 820, "Fair Value Measurement" and primarily consist of expected future operating margins and cash flows, estimated production volumes, weighted average cost of capital rates (13.0%), estimated salable values and third-party appraisal techniques such as market comparables. To the extent that profitability on current or future programs decline as compared to forecasted profitability or if adverse changes occur to key assumptions or other fair value measurement inputs, further impairment of long-lived assets could occur in the future. Refer to Note 6, "Goodwill and Other Intangible Assets," and Note 5, "Property, Plant and Equipment," of the notes to the consolidated financial statements for additional information. See Note 19, "Nonconsolidated Partially-Owned Affiliates," for information on the fiscal 2020 and 2018 impairment of investments in partially owned affiliates.