Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Accumulated other comprehensive income [Roll Forward]
Beginning balance			$ 7,618
Ending balance	$ 8,022		8,022
Accumulated other comprehensive income (loss)	(1,575)	$ (1,564)	(1,575)	$ (1,564)	$ (1,999)
Foreign currency translation [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(655)	(651)	(812)	(622)
Other comprehensive income (loss) before reclassifications	75	(10)	(153)	(39)
Reclassified to gain/loss on sale of businesses	0	0	385	0
Ending balance	(580)	(661)	(580)	(661)
Pension and post retirement [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(1,042)	(899)	(1,162)	(952)
Amortization of deferred actuarial losses into earnings	35	25	105	78
Reclassified to gain/loss on sale of businesses	0	0	50	0
Ending balance	(1,007)	(874)	(1,007)	(874)
Cash Flow Hedges [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	7	(32)	(25)	(43)
Deferral of gains (losses) arising during the period	7	(11)	30	(22)
Reclassification of realized (gains) losses to sales and cost of sales	(2)	14	7	36
Ending balance	$ 12	$ (29)	$ 12	$ (29)