Share-Based Compensation (Market-Based Deferred Stock Unit Valuation Assumptions) (Details) - Market-Based Deferred Stock Unit	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	32.50%	30.50%	29.90%
Risk-free interest rate	4.00%	0.80%	0.20%
Expected dividend yield	2.40%	2.10%	2.10%