Segment Information - Financial Information Related to Company's Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net sales	$ 9,608	$ 9,833	$ 28,430	$ 28,797
Segment Income	822	630	2,208	1,844
Net financing charges	(75)	(67)	(215)	(178)
Restructuring and impairment costs	0	(162)	0	(162)
Income from continuing operations before income taxes	747	401	1,993	1,504
Power Solutions
Segment Reporting Information [Line Items]
Net sales	1,473	1,506	4,905	4,842
Segment Income	234	192	813	732
Building Efficiency
Segment Reporting Information [Line Items]
Net sales	2,733	2,597	7,607	7,181
Segment Income	260	245	583	497
Building Efficiency | North America Systems and Service
Segment Reporting Information [Line Items]
Net sales	1,156	1,126	3,192	3,141
Segment Income	132	136	318	302
Building Efficiency | Building Efficiency Asia
Segment Reporting Information [Line Items]
Net sales	493	521	1,409	1,480
Segment Income	77	83	196	212
Building Efficiency | Building Efficiency Other
Segment Reporting Information [Line Items]
Net sales	1,084	950	3,006	2,560
Segment Income	51	26	69	(17)
Automotive Experience
Segment Reporting Information [Line Items]
Net sales	5,402	5,730	15,918	16,774
Segment Income	328	193	812	615
Automotive Experience | Seating
Segment Reporting Information [Line Items]
Net sales	4,255	4,571	12,531	13,364
Segment Income	273	249	703	648
Automotive Experience | Interiors
Segment Reporting Information [Line Items]
Net sales	1,147	1,159	3,387	3,410
Segment Income	$ 55	$ (56)	$ 109	$ (33)