Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016
Accumulated other comprehensive income [Roll Forward]
Beginning balance	$ 7,618
Ending balance	7,754
Accumulated other comprehensive income (loss)	(2,030)	$ (1,738)	$ (1,999)
Foreign currency translation [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(812)	(622)
Other comprehensive income (loss) before reclassifications	(367)	(153)
Divestiture of business reclassified to gain on sale	266	0
Ending balance	(913)	(775)
Pension and post retirement [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(1,162)	(952)
Amortization of deferred actuarial losses into earnings	35	26
Divestiture of business reclassified to gain on sale	20	0
Ending balance	(1,107)	(926)
Cash Flow Hedges [Member]
Accumulated other comprehensive income [Roll Forward]
Beginning balance	(25)	(43)
Deferral of gains (losses) arising during the period	8	(3)
Reclassification of realized (gains) losses to sales and cost of sales	7	9
Ending balance	$ (10)	$ (37)