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Financial Instruments (Net Investment Hedge) (Details) € in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	May 31, 2019 EUR (€)	Jan. 31, 2019 EUR (€)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to other comprehensive income, pretax \| $	$ (8)	$ (18)	$ 5	$ (18)
Foreign Exchange Contract [Member] \| Net Investment Hedging [Member] \| Other Comprehensive Income (Loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to other comprehensive income, pretax \| $	6		12
Gain (loss) to other comprehensive income, after-tax \| $	$ 4		$ 9
1.25 Percent Notes Due October 2025 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt, face amount \| €						€ 500
Notes interest rate, percentage						1.25%
2.0 Percent Notes Due October 2029 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt, face amount \| €						€ 500
Notes interest rate, percentage						2.00%
0.375 Percent Notes Due May 2024 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt, face amount \| €					€ 500
Notes interest rate, percentage					0.375%