| Document and Entity Information - USD ($) $ in Billions | 12 Months Ended | |
| Sep. 30, 2019 | Mar. 31, 2019 | |
| Document and Entity Information [Abstract] | ||
| Document Type | 10-K/A | |
| Document Annual Report | true | |
| Document Period End Date | Sep. 30, 2019 | |
| Document Transition Report | false | |
| Entity File Number | 001-37757 | |
| Entity Registrant Name | Adient plc | |
| Entity Incorporation, State or Country Code | L2 | |
| Entity Tax Identification Number | 98-1328821 | |
| Entity Address, Address Line One | 25-28 North Wall Quay | |
| Entity Address, Address Line Two | IFSC | |
| Entity Address, City or Town | Dublin 1 | |
| Entity Address, Country | IE | |
| Entity Address, Postal Zip Code | D01 H104 | |
| City Area Code | 734 | |
| Local Phone Number | 254-5000 | |
| Title of 12(b) Security | Ordinary Shares, par value $0.001 | |
| Trading Symbol | ADNT | |
| Security Exchange Name | NYSE | |
| Entity Well-known Seasoned Issuer | Yes | |
| Entity Voluntary Filers | No | |
| Entity Current Reporting Status | Yes | |
| Entity Interactive Data Current | Yes | |
| Entity Filer Category | Large Accelerated Filer | |
| Entity Small Business | false | |
| Entity Emerging Growth Company | false | |
| Entity Shell Company | false | |
| Entity Public Float | $ 1.2 | |
| Entity Common Stock, Shares Outstanding | 93,620,714 | |
| Entity Central Index Key | 0001670541 | |
| Current Fiscal Year End Date | --09-30 | |
| Document Fiscal Year Focus | 2019 | |
| Document Fiscal Period Focus (Q1,Q2,Q3,FY) | FY | |
| Amendment Flag | true | |
| Amendment Description | An amendment to include the separate financial statements of YFAS |
| SEC Schedule, Article 12-09, Valuation and Qualifying Accounts | 12 Months Ended |
| Sep. 30, 2019 | |
| SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] | |
| SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS | SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS Year Ended (in millions) 2019 2018 2017 Accounts Receivable - Allowance for Doubtful Accounts Balance at beginning of period $ 15 $ 20 $ 21 Provision charged to costs and expenses 15 12 13 Reserve adjustments (16) (17) (14) Balance at end of period $ 14 $ 15 $ 20 Deferred Tax Assets - Valuation Allowance Balance at beginning of period $ 846 $ 223 $ 267 Allowance provision for new operating and other loss carryforwards 488 669 23 Allowance provision (benefit) adjustments (30) (46) (67) Balance at end of period $ 1,304 $ 846 $ 223 |
| SEC Schedule, Article 12-09, Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions | 12 Months Ended | ||
| Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017 | |
| SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset | |||
| SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] | |||
| SEC Schedule, 12-09, valuation allowances and reserves, amount, beginning balance | $ 846 | $ 223 | $ 267 |
| Provision during period | 488 | 669 | 23 |
| Allowance adjustments | (30) | (46) | (67) |
| SEC Schedule, 12-09, valuation allowances and reserves, amount, ending balance | 1,304 | 846 | 223 |
| SEC Schedule, 12-09, Allowance, Doubtful Accounts | |||
| SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] | |||
| SEC Schedule, 12-09, valuation allowances and reserves, amount, beginning balance | 15 | 20 | 21 |
| Provision during period | 15 | 12 | 13 |
| Allowance adjustments | (16) | (17) | (14) |
| SEC Schedule, 12-09, valuation allowances and reserves, amount, ending balance | $ 14 | $ 15 | $ 20 |
