Stock Incentive Plans - Components of Pre-Tax Stock-Based Compensation Expense Included in Continuing Operations (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023		Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1	[1]	$ 8	[2]
Cash-settled Nonvested Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1		$ 1
Cash-settled Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1

[1] Included less than $1 million of expense related to cash-settled nonvested restricted stock awards during the three months ended December 31, 2023, and $1 million of income related to cash-settled performance units during the three months ended December 31, 2023.

[2] Included $1 million of expense related to cash-settled nonvested restricted stock awards during the three months ended December 31, 2022.