Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended			15 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Tax benefit from restructuring foreign subsidiary	$ 13	$ 103	$ 74
Payroll tax deferral from CARES Act				$ 73
Non-U.S. tax holiday tax rate reductions for certain foreign jurisdictions, expiration period in years	1 year
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 50
Unrecognized tax benefits that would impact effective tax rate	185
Unrecognized tax benefits, income tax penalties and interest expense	(4)	1	4
Unrecognized tax benefits, income tax penalties and interest accrued	24	29
Income taxes paid	$ 680	$ 400	$ 650
Amount of net operating losses and tax credits expiring over the next 10 years	Approximately half
Net operating losses and tax credits, remaining to expire over next 10 years	$ 316