Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Gains (Losses) deferred in accumulated other comprehensive income will be amortized into earnings in 2018		$ (142)
Losses deferred in accumulated other comprehensive income		(1,161)
Total accumulated benefit obligation		5,607	$ 5,729
Accumulated benefit obligations in excess of plan assets for retirement plans, projected benefit obligation		1,182	5,951
Accumulated benefit obligations in excess of plan assets for retirement plans, accumulated benefit obligation		1,088	5,678
Accumulated benefit obligations in excess of plan assets for retirement plans, fair value of plan assets		663	4,958
Pension contribution		45	66	$ 53
Pension expense		127	95	$ 153
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan		(77)	$ (586)
Over (Under) funded plans		(77)
Unfunded plans		(201)
Future benefit payments, 2018		212
Future benefit payments, 2019		220
Future benefit payments, 2020		228
Future benefit payments, 2021		235
Future benefit payments, 2022		241
Total future benefit payments, 2023 - 2027		$ 1,272
Discount rate		3.76%	3.50%	4.35%
Pension expense		$ 115	$ 77	$ 122
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan		(253)	$ (411)
Over (Under) funded plans		(253)
Unfunded plans		(215)
Future benefit payments, 2018		56
Future benefit payments, 2019		57
Future benefit payments, 2020		59
Future benefit payments, 2021		63
Future benefit payments, 2022		68
Total future benefit payments, 2023 - 2027		$ 390
Discount rate		2.60%	2.30%	3.30%
Pension expense		$ 15	$ 30	$ 45
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension contribution	$ 60
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
Discontinued Operations, Disposed of by Sale [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense		3
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plans		96	104	111
U.S. Plans [Member] | Discontinued Operations, Held-for-sale [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plans			$ 34	$ 33
U.S. Plans [Member] | Discontinued Operations, Disposed of by Sale [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plans		$ 6