Financial Instruments (Schedule Of Derivative Instruments) (Details) lb in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018 USD ($) lb	Mar. 31, 2017 USD ($)	Mar. 31, 2018 USD ($) lb	Mar. 31, 2017 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to earnings	$ (6)	$ (9)	$ (1)	$ (15)
Gain (loss) to other comprehensive income	(1)	25	0	37
Commodity Contract [Member] | Cash Flow Hedging [Member] | Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to other comprehensive income	(9)	5	4	15
Commodity Contract [Member] | Cash Flow Hedging [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified to earnings	6	4	11	2
Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of foreign currency hedge positions	1,600		1,600
Foreign Exchange Contract [Member] | Other deductions, net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to earnings	(12)	(6)	(12)	0
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to other comprehensive income	8	20	(4)	22
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | Sales, Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified to earnings	0	$ (7)	0	$ (17)
All Commodity Hedges [Member] [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of commodities hedged	$ 140		$ 140
Copper and Aluminum [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Weight in pounds of copper and aluminum commodity hedges | lb	53		53