Segment Information Financial Information Related to Company's Reportable Segments (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Segment Information [Line Items]
Net Sales		$ 37,674	$ 37,179	$ 38,749
Segment Income		3,023	3,258	2,721
Net financing charges		(314)	(288)	(244)
Restructuring and impairment costs		(620)	(397)	(324)
Equity income in segment income		531	375	395
Net mark-to-market adjustments on pension and postretirement plans		503	422	237
Income from continuing operations before income taxes		1,586	2,151	1,916
Total assets		63,253	29,622	32,812
Assets held for sale		174	55	2,787
Depreciation and amortization		953	860	955
Capital expenditures		1,249	1,135	1,199
Building Efficiency
Segment Information [Line Items]
Net Sales		13,376	10,510	10,085
Segment Income		1,036	923	817
Total assets		11,658	9,383	9,558
Depreciation and amortization		280	197	160
Capital expenditures		376	268	239
Building Efficiency | Building Efficiency Systems and Service North America [Member]
Segment Information [Line Items]
Net Sales		4,292	4,184	4,098
Segment Income	[1]	412	375	354
Restructuring and impairment costs		(2)	(3)	(12)
Total assets		2,338	2,332	2,341
Depreciation and amortization		38	32	32
Capital expenditures		15	22	27
Building Efficiency | Building Efficiency Products North America [Domain]
Segment Information [Line Items]
Restructuring and impairment costs		(9)	(11)	(7)
Building Efficiency | Building Efficiency Products North America [Member]
Segment Information [Line Items]
Net Sales		2,488	2,450	1,807
Segment Income	[2]	173	306	238
Equity income in segment income		10	9	7
Total assets		4,236	4,193	4,157
Depreciation and amortization		116	119	79
Capital expenditures		217	160	123
Building Efficiency | Global Workplace Solutions
Segment Information [Line Items]
Capital expenditures		0	16	16
Building Efficiency | Building Efficiency Asia
Segment Information [Line Items]
Net Sales		4,830	1,985	2,077
Segment Income	[3]	431	191	270
Restructuring and impairment costs		(26)	(11)	(4)
Equity income in segment income		100		21
Total assets		3,668	1,387	1,418
Depreciation and amortization		107	27	24
Capital expenditures		119	32	39
Building Efficiency | Building Efficiency Other
Segment Information [Line Items]
Net Sales		1,766	1,891	2,103
Segment Income	[4]	20	51	(45)
Restructuring and impairment costs		(16)	(13)	(119)
Equity income in segment income		15	14	7
Total assets		1,416	1,471	1,642
Depreciation and amortization		19	19	25
Capital expenditures		25	38	34
Building Efficiency | Buildings Tyco [Member]
Segment Information [Line Items]
Net Sales		808	0	0
Total assets		28,097	0	0
Depreciation and amortization		53	0	0
Capital expenditures		22	0	0
Buildings Tyco [Member]
Segment Information [Line Items]
Segment Income	[5]	(17)	0	0
Buildings [Member]
Segment Information [Line Items]
Net Sales		14,184	10,510	10,085
Segment Income		1,019	923	817
Total assets		39,755	9,383	9,558
Depreciation and amortization		333	197	160
Capital expenditures		398	268	239
Buildings [Member] | Buildings Tyco [Member]
Segment Information [Line Items]
Restructuring and impairment costs		(85)
Equity income in segment income		1
Automotive Experience
Segment Information [Line Items]
Net Sales		16,837	20,079	22,032
Segment Income		751	1,182	852
Total assets		10,152	9,876	9,290
Depreciation and amortization		368	366	456
Capital expenditures		447	558	632
Automotive Experience | Seating
Segment Information [Line Items]
Net Sales		16,355	16,539	17,531
Segment Income	[6]	676	928	853
Restructuring and impairment costs		(284)	(182)	(29)
Equity income in segment income		289	264	250
Total assets		8,888	8,611	8,969
Depreciation and amortization		355	345	328
Capital expenditures		444	437	420
Automotive Experience | Interiors
Segment Information [Line Items]
Net Sales		482	3,540	4,501
Segment Income	[7]	75	254	(1)
Restructuring and impairment costs		(17)		(130)
Equity income in segment income		68	31	35
Total assets	[8]	1,264	1,265	321
Depreciation and amortization		13	21	128
Capital expenditures		3	121	181
Automotive Experience | Automotive Experience Electronics
Segment Information [Line Items]
Capital expenditures		0	0	31
Power Solutions
Segment Information [Line Items]
Net Sales		6,653	6,590	6,632
Segment Income	[9]	1,253	1,153	1,052
Restructuring and impairment costs		(66)	(11)	(16)
Equity income in segment income		48	57	75
Total assets		6,859	6,590	6,888
Depreciation and amortization		252	297	315
Capital expenditures		404	309	328
Unallocated
Segment Information [Line Items]
Total assets		6,313	3,718	4,289
Discontinued Operations
Segment Information [Line Items]
Depreciation and amortization		$ 0	$ 0	$ 24

[1] Building Efficiency - Systems and Service North America segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $2 million, $3 million and $12 million, respectively, of restructuring and impairment costs.

[2] Building Efficiency - Products North America segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $9 million, $11 million and $7 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016, 2015 and 2014, Products North America segment EBIT includes $10 million, $9 million and $7 million, respectively, of equity income.

[3] Building Efficiency - Asia segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $26 million,$11 million and $4 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016 and 2014, Asia segment EBIT includes $100 million and $21 million, respectively, of equity income.

[4] Building Efficiency - Rest of World segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $16 million, $13 million and $119 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016, 2015 and 2014, Rest of World segment EBIT includes $15 million, $14 million and $7 million, respectively, of equity income.

[5] Tyco segment EBIT for the year ended September 30, 2016 excludes $85 million of restructuring and impairment costs. For the year ended September 30, 2016, Tyco segment EBIT includes $1 million of equity income.

[6] Automotive Experience - Seating segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $284 million, $182 million and $29 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016, 2015 and 2014, Seating segment EBIT includes $289 million, $264 million and $250 million, respectively, of equity income.

[7] Automotive Experience - Interiors segment EBIT for the years ended September 30, 2016 and 2014 excludes $17 million and $130 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016, 2015 and 2014, Interiors segment EBIT includes $68 million, $31 million and $35 million, respectively, of equity income.

[8] Current year and prior year amounts exclude assets held for sale. Refer to Note 4, "Discontinued Operations," of the notes to consolidated financial statements for further information regarding the Company's disposal groups classified as held for sale.

[9] Power Solutions segment EBIT for the years ended September 30, 2016, 2015 and 2014 excludes $66 million, $11 million and $16 million, respectively, of restructuring and impairment costs. For the years ended September 30, 2016, 2015 and 2014, Power Solutions segment EBIT includes $48 million, $57 million and $75 million, respectively, of equity income.