Income Taxes - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended			15 Months Ended
	Dec. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Payroll taxes deferred					$ 73
Payroll taxes paid	$ 37
Tax holiday expiration, percent		80.00%
Tax holiday expiration, term of expiration		4 years
Unrecognized tax benefits that would impact effective tax rate		$ 196
Unrecognized tax benefits, income tax penalties and interest expense (income)		1	$ (7)	$ (6)
Unrecognized tax benefits, income tax penalties and interest accrued		22	21
Income taxes paid		3,310	$ 720	$ 680
Net operating losses and tax credits, amount available to carry forward		$ 253
Net operating losses and tax credits, additional amount available to carry forward, term		10 years
Percentage of net operating losses and tax credits that can be carried forward		66.67%
Copeland
Income Tax Contingency [Line Items]
Income taxes paid		$ 2,300