Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Accumulated other comprehensive income [Roll Forward]
Stockholders' equity, Beginning balance	$ 8,128	$ 10,167
Stockholders' equity, Ending balance	7,618	8,128	$ 10,167
Accumulated other comprehensive income (loss)	(1,999)	(1,617)	(575)
Foreign currency translation
Accumulated other comprehensive income [Roll Forward]
Stockholders' equity, Beginning balance	(622)	171	504
Other comprehensive income (loss)	(190)	(793)	(341)
Purchase of noncontrolling interest	0	0	8
Stockholders' equity, Ending balance	(812)	(622)	171
Pension and postretirement
Accumulated other comprehensive income [Roll Forward]
Stockholders' equity, Beginning balance	(952)	(746)	(692)
Actuarial gains (losses) deferred during the period	(310)	(315)	(152)
Amortization of deferred actuarial losses into earnings	100	109	98
Stockholders' equity, Ending balance	(1,162)	(952)	(746)
Actuarial gains (losses) deferred during the period, tax	159	192	87
Amortization of deferred actuarial (gains) losses into earnings, tax	(59)	(59)	(52)
Cash flow hedges
Accumulated other comprehensive income [Roll Forward]
Stockholders' equity, Beginning balance	(43)	0	(1)
Gains (Losses) deferred during the period	(30)	(66)	(1)
Reclassifications of realized (gains) losses to sales and cost of sales	48	23	2
Stockholders' equity, Ending balance	(25)	(43)	0
Gains (losses) deferred during the period, tax	17	38	0
Reclassification of (gains) losses to sales and cost of sales, tax	(28)	(13)	0
Discontinued Operations, Held-for-sale [Member] | Pension and postretirement
Accumulated other comprehensive income [Roll Forward]
Amortization of deferred actuarial losses into earnings	$ (3)	$ (3)	$ (2)