Goodwill and Other Intangible Assets - Goodwill (Details) $ in Millions	6 Months Ended
	Mar. 31, 2021 USD ($)
Goodwill [Roll Forward]
Balance at September 30, 2020	$ 2,057
Currency translation and other	2
Balance at March 31, 2021	2,059
Americas
Goodwill [Roll Forward]
Balance at September 30, 2020	606
Currency translation and other	(1)
Balance at March 31, 2021	605
EMEA
Goodwill [Roll Forward]
Balance at September 30, 2020	368
Currency translation and other	1
Balance at March 31, 2021	369
Asia
Goodwill [Roll Forward]
Balance at September 30, 2020	1,083
Currency translation and other	2
Balance at March 31, 2021	$ 1,085