Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Income Tax Examination [Line Items]
Effective income tax rate	22.00%	52.70%	16.00%	21.50%
Gross tax effected unrecognized tax benefits					$ 2,537
Amount of unrecognized tax benefits which may impact effective tax rate					1,973
Total net accrued interest, net of tax benefit					$ 284
Unrecognized tax benefits, income tax penalties and interest expense			$ 56	$ 30
Restructuring and impairment costs	$ 418	$ 384	763	433
Restructuring charges, tax benefit	$ 35	7	$ 87	14
Effective income tax rate reconciliation, repatriation of foreign earnings, amount		$ 13		$ 13
IRELAND
Income Tax Examination [Line Items]
Ireland statutory income tax rate	12.50%	12.50%	12.50%	12.50%