Regulatory Matters (Details) $ in Millions	6 Months Ended
	Mar. 31, 2020 USD ($)
Supply Corporation [Member]
Regulatory Matters [Line Items]
Estimated Annual Increase to Revenues from Period 1 Interim Rates	$ 35.5
Additional Estimated Annual Revenue Increase from Implementation of Period 2 Rates	$ 15.0
NEW YORK
Regulatory Matters [Line Items]
Approved Return on Equity	8.70%