Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Losses deferred in accumulated other comprehensive income will be amortized into earnings in 2017		$ 234
Losses deferred in accumulated other comprehensive income		1,916
Total accumulated benefit obligation		5,729	$ 5,254
Accumulated benefit obligations in excess of plan assets for retirement plans, projected benefit obligation		5,951	1,245
Accumulated benefit obligations in excess of plan assets for retirement plans, accumulated benefit obligation		5,678	1,139
Accumulated benefit obligations in excess of plan assets for retirement plans, fair value of plan assets		4,958	648
Pension contribution		66	53	$ 130
Pension expense		95	153	$ 142
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan		(586)	$ (335)
Over (Under) funded plans		(586)
Unfunded plans		216
Future benefit payments, 2017		215
Future benefit payments, 2018		224
Future benefit payments, 2019		233
Future benefit payments, 2020		241
Future benefit payments, 2021		249
Total future benefit payments, 2022 - 2026		$ 1,326
Discount rate		3.50%	4.35%	4.25%
Pension expense		$ 77	$ 122	$ 108
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan		(411)	$ (313)
Over (Under) funded plans		(411)
Unfunded plans		237
Future benefit payments, 2017		41
Future benefit payments, 2018		42
Future benefit payments, 2019		45
Future benefit payments, 2020		47
Future benefit payments, 2021		51
Total future benefit payments, 2022 - 2026		$ 306
Discount rate		2.30%	3.30%	3.60%
Pension expense		$ 30	$ 45	$ 45
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension contribution	$ 40
Change in Assumptions for Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in Estimated Service Cost and Interest Cost for Pension Expense		38
Discontinued Operations, Held-for-sale [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense		12	14	11
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plans		104	111	119
U.S. Plans [Member] | Discontinued Operations, Held-for-sale [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plans		$ 34	$ 33	$ 33