Financial Statements - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) Segment Entity	Mar. 31, 2018 USD ($) Segment Entity	Jun. 30, 2017 Segment	Sep. 30, 2017 USD ($) Entity	Sep. 30, 2012 InterestInvestment Entity	Oct. 31, 2016 shares
Financial Statement Details [Line Items]
Number of Countries in which Entity Operates		150
Adient shares received per 10 shares of Johnson Controls shares | shares						1
Johnson Controls shares converted into one share of Adient | shares						10
Interest percentage minimum for investments in partially-owned affiliates to be accounted for by the equity method		20.00%
Number of VIEs where Company is Primary Beneficiary | Entity	1			1
Number of separate investments a pre-existing VIE was reorganized into | Entity					3
Additional interests acquired | InterestInvestment					2
Third party debt agreement		$ 159
Loans to partially-owned affiliates		37
Floor guarantee		$ 25
Number of VIEs in which Company was not primary beneficiary | Entity		3		2
Restricted Cash and Cash Equivalents	$ 31	$ 21		$ 31
Restricted Cash and Investments, Current	22	12		22
Restricted Cash and Cash Equivalents, Noncurrent	9	$ 9		9
Number of reportable segments | Segment		5
Variable Interest Entity, Not Primary Beneficiary [Member]
Financial Statement Details [Line Items]
Investment balance of the Company's nonconsolidated VIEs	$ 65	$ 41		$ 65
Power Solutions
Financial Statement Details [Line Items]
Number of VIEs where Company is Primary Beneficiary | Entity		1
Building Technologies & Solutions
Financial Statement Details [Line Items]
Number of reportable segments | Segment	4		5