Capitalization and Short-Term Borrowings - Weighted Average Assumptions Used in Estimating Fair Value (Details) - Performance Shares	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-Free Interest Rate	4.11%	4.36%	4.03%
Remaining Term at Date of Grant (Years)	2 years 9 months 25 days	2 years 11 months 23 days	2 years 9 months 18 days
Expected Volatility	23.20%	23.90%	31.60%