Accounting Changes (Details) - USD ($) $ in Millions	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature	$ 5,188	$ 6,074	$ 5,359
Common Stock | Cumulative effect of change in accounting - ASU 2020-06 (Note 3)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature		(6)
Preferred Stock
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature	167	162	214	$ 213
Preferred Stock | Cumulative effect of change in accounting - ASU 2020-06 (Note 3)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature		6		5
Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature	$ 3,808	4,841	$ 3,908	4,081
Retained Earnings | Cumulative effect of change in accounting - ASU 2020-06 (Note 3)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beneficial conversion feature		$ 1		$ 1