Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Carrying Amounts and Classifications of Assets and Liabilities for Consolidated VIEs (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Variable Interest Entity [Line Items]
Current assets	$ 5,091	$ 5,086
Total assets	10,719	10,778
Current liabilities	3,742	3,511
Noncurrent liabilities	4,257	4,309
VIEs
Variable Interest Entity [Line Items]
Current assets	189	158
Noncurrent assets	99	88
Total assets	288	246
Current liabilities	155	143
Noncurrent liabilities	14	8
Total liabilities	$ 169	$ 151