Summary of Significant Accounting Policies Accounting Policies (Details)	12 Months Ended
	Sep. 30, 2016 USD ($) Segment $ / shares	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2014 USD ($)	Sep. 02, 2016 $ / shares
Financial Statement Details [Line Items]
Liability for Asbestos and Environmental Claims, Gross	$ 548,000,000
Maturity period to be considered cash equivalents	3 months
Engineering and research and development costs to be reimbursed	$ 316,000,000	$ 299,000,000
Expected reimbursement period of less than one year	1 year
Expected reimbursement period beyond one year	1 year
Molds, dies and other tools costs capitalized within property, plant and equipment	$ 62,000,000	60,000,000
Molds, dies and other tools costs to be reimbursed	203,000,000	149,000,000
Costs and earnings in excess of billings related to contracts	841,000,000	453,000,000
Billing in excess of costs and earnings on uncompleted contracts	$ 431,000,000	340,000,000
Timing of the first deliverable to the last delivery	Approximately four to twelve months
Research activities costs relating to product development and improvement, net of customer reimbursements	$ 618,000,000	733,000,000	$ 792,000,000
Customer reimbursements included in research activities costs	308,000,000	364,000,000	352,000,000
Foreign currency transaction losses	$ 95,000,000	119,000,000	$ 8,000,000
Number of reportable segments | Segment	8
Cash in escrow related to Adient debt	$ 2,034,000,000	0
Proceeds from Issuance of Unsecured Debt	2,000,000,000
Restricted Cash and Cash Equivalents	88,000,000	$ 0.00
Restricted Cash and Investments, Current	79,000,000
Restricted Cash and Cash Equivalents, Noncurrent	$ 9,000,000
Common stock, par value | $ / shares	$ 0.01	$ 0.01		$ 1.00
Pooled subscriber assets and related deferred revenue, useful life	15 years
Non-pooled subscriber assets and related deferred revenue, useful life	15 years
Standard chargeback period from dealer for monitoring service cancellations	6 months
Non-standard chargeback period from dealer for monitoring service cancellations	12 months
Minimum
Financial Statement Details [Line Items]
Duration of extended warranty arrangements	1 year
Estimated useful life of dealer intangible assets	12 years
Maximum
Financial Statement Details [Line Items]
Duration of extended warranty arrangements	5 years
Estimated useful life of dealer intangible assets	15 years
Building And Improvements | Minimum
Financial Statement Details [Line Items]
Estimated useful lives	3 years
Building And Improvements | Maximum
Financial Statement Details [Line Items]
Estimated useful lives	40 years
Machinery and Equipment | Minimum
Financial Statement Details [Line Items]
Estimated useful lives	3 years
Machinery and Equipment | Maximum
Financial Statement Details [Line Items]
Estimated useful lives	15 years
Johnson Controls International plc [Member]
Financial Statement Details [Line Items]
Proceeds from Issuance of Unsecured Debt	$ 1,500,000,000
Adient [Member]
Financial Statement Details [Line Items]
Proceeds from Issuance of Unsecured Debt	500,000,000
Asbestos Issue [Member]
Financial Statement Details [Line Items]
Liability for Asbestos and Environmental Claims, Gross	68,000,000
Other noncurrent assets | Asbestos Issue [Member]
Financial Statement Details [Line Items]
Liability for Asbestos and Environmental Claims, Gross	27,000,000
Retained Earnings | Asbestos Issue [Member]
Financial Statement Details [Line Items]
Liability for Asbestos and Environmental Claims, Gross	$ 41,000,000
Tyco Merger [Member]
Financial Statement Details [Line Items]
Common stock, par value | $ / shares	$ 1.00