Significant Restructuring and Impairment Costs (Detail) $ in Millions	3 Months Ended			12 Months Ended				48 Months Ended
	Sep. 30, 2016 USD ($) Plant Employees	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) Plant Employees	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2016 Plant Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				$ 620	$ 397	$ 324
Number of employees to be severed | Employees								18,900
Restructuring and Related Cost, Number of Positions Eliminated, Inception to Date | Employees	11,800			11,800				11,800
Restructuring And Related Cost Expected Number Of Plants To Be Closed | Plant				30
Number Of Plants Closed | Plant	12			12				12
Automotive Experience
Restructuring Cost and Reserve [Line Items]
Number of employees to be severed | Employees								11,200
Restructuring And Related Cost Expected Number Of Plants To Be Closed | Plant				22
Building Efficiency
Restructuring Cost and Reserve [Line Items]
Number of employees to be severed | Employees								6,700
Restructuring And Related Cost Expected Number Of Plants To Be Closed | Plant				8
Power Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				$ 66	11	16
Number of employees to be severed | Employees								900
2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				620
2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 289	$ 102	$ 229	620
2016 Restructuring Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				368
Committed restructuring liabilities assumed from Tyco Merger [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				78
Committed restructuring liabilities assumed from Tyco Merger [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				78
2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					397
2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					397
2015 Restructuring Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					191
2014 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						377
2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						324
2014 Restructuring Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						191
2014 Restructuring Plan | Automotive Experience Electronics | Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						53
2013 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							$ 985
2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							903
2013 Restructuring Plan | Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							82
2013 Restructuring Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							392
2013 Restructuring Plan | Automotive Experience Electronics | Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							28
2013 Restructuring Plan | Global Workplace Solutions | Discontinued Operations
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							54
Building Efficiency Systems and Service North America [Member] | Building Efficiency
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				2	3	12
Building Efficiency Systems and Service North America [Member] | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				2
Building Efficiency Systems and Service North America [Member] | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					3
Building Efficiency Systems and Service North America [Member] | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						12
Building Efficiency Systems and Service North America [Member] | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							35
Corporate | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				115
Corporate | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					166
Corporate | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						7
Corporate | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							17
Automotive Experience Interiors | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				17
Automotive Experience Interiors | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						130
Automotive Experience Interiors | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							560
Building Efficiency Other | Building Efficiency
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				16	13	119
Building Efficiency Other | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				16
Building Efficiency Other | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					13
Building Efficiency Other | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						119
Building Efficiency Other | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							70
Building Efficiency Products North America [Member] | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				9
Building Efficiency Products North America [Member] | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					11
Building Efficiency Products North America [Member] | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						7
Building Efficiency Products North America [Member] | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							28
Automotive Experience Seating | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				284
Automotive Experience Seating | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					182
Automotive Experience Seating | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						29
Automotive Experience Seating | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							152
Power Solutions | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				66
Power Solutions | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					11
Power Solutions | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						16
Power Solutions | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							36
Building Efficiency Asia | Building Efficiency
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				26	11	4
Building Efficiency Asia | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				26
Building Efficiency Asia | 2015 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					$ 11
Building Efficiency Asia | 2014 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs						$ 4
Building Efficiency Asia | 2013 Restructuring Plan | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs							$ 5
Buildings Tyco [Member] | 2016 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				85
Buildings Tyco [Member] | Committed restructuring liabilities assumed from Tyco Merger [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				$ 78