Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Accumulated other comprehensive income [Roll Forward]
Beginning balance			$ 8,128
Ending balance	$ 7,743		7,743
Accumulated other comprehensive income (loss)	(1,582)	$ (1,273)	(1,582)	$ (1,273)	$ (1,617)
Foreign currency translation [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(775)	(133)	(622)	171
Other comprehensive income (loss)	124	(427)	(29)	(731)
Ending balance	(651)	(560)	(651)	(560)
Pension and post retirement [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(926)	(718)	(952)	(746)
Amortization of deferred actuarial losses into earnings	27	27	53	55
Divestiture of business	0	1	0	1
Ending balance	(899)	(690)	(899)	(690)
Cash Flow Hedges [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(37)	(24)	(43)	0
Deferral of gains (losses) arising during the period	(8)	(3)	(11)	(29)
Reclassification of realized (gains) losses to sales and cost of sales	13	4	22	6
Ending balance	$ (32)	$ (23)	$ (32)	$ (23)