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Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Long-term debt	$ 4,064	$ 4,318
Less: Current maturities	270	267
Total, net	3,794	4,051
Long-term debt maturing during year two	683
Long-term debt maturing during year three	516
Long-term debt maturing during year four	299
Long-term debt maturing during year five	500
Interest paid related to short-term borrowings and long-term debt	192	209	$ 196
5.125% notes due December 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	0	250
Repayments of debt	$ 250
Notes interest rate, percentage	5.125%
5.375% notes due October 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	250
5.25% notes due October 2018[Member]
Debt Instrument [Line Items]
Long-term debt	400	400
5.0% notes due April 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	250	250
4.875% notes due October 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	500	500
4.25% notes due November 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	300	300
2.625% Notes Due December 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	500	500
2.625% notes due February 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	500	500
3.15% Notes Due June 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	500	500
6.0% notes due August 2032 [Member]
Debt Instrument [Line Items]
Long-term debt	250	250
6.125% notes due April 2039 [Member]
Debt Instrument [Line Items]
Long-term debt	250	250
5.25% notes due November 2039 [Member]
Debt Instrument [Line Items]
Long-term debt	300	300
Other [Member]
Debt Instrument [Line Items]
Long-term debt	$ 64	68
4.75% notes due October 2015 [Member]
Debt Instrument [Line Items]
Repayments of debt		$ 250
Notes interest rate, percentage		4.75%