Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2021
Income Taxes, Additional Information [Line Items]
Effective income tax rate	12.10%	14.00%	17.20%	20.90%
Ireland statutory income tax rate	12.50%	12.50%	12.50%	12.50%
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 105
Gross tax effected unrecognized tax benefits					$ 2,726
Amount of unrecognized tax benefits which may impact effective tax rate					2,268
Total net accrued interest, net of tax benefit					$ 252
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense			$ 40	$ 37
Mark-to-market gain (loss)	$ (126)	66	(158)	296
Mark-to-market gain (loss), tax expense (benefit)	(33)	17	(40)	75
Restructuring and impairment costs	121	79	554	175
Restructuring charges, tax benefit	15	$ 15	29	$ 30
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	8		21
Business Acquisition, Transaction Costs	9		9
Business Acquisition, Transaction Costs, Tax	$ 1		$ 1