Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Disclosure - Gains (Losses) on Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Foreign Exchange Contract
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency-denominated debt	$ 39	$ 158	$ 81	$ 53
Currency Swap
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency-denominated debt	(14)	0	(14)	0
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency-denominated debt	$ (9)	$ 0	$ (9)	$ 0