Goodwill and Other Intangible Assets - Other Intangible Assets Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 100	$ 108	$ 288	$ 383
Future amortization expense, 2019	388		388
Future amortization expense, 2020	380		380
Future amortization expense, 2021	371		371
Future amortization expense, 2022	365		365
Future amortization expense, 2023	$ 344		$ 344