Regulatory Matters (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Regulatory Matters [Line Items]
Reduction of Other Post-Retirement Regulatory Liability	$ (18,533)	$ 0
NEW YORK
Regulatory Matters [Line Items]
Approved Return on Equity	8.70%
PENNSYLVANIA
Regulatory Matters [Line Items]
Base Rate Reduction	$ (7,700)
Proposed Refund to Customers from Over-Collection of OPEB Expenses	50,000
Approved Refund to Customers from Over-Collection of OPEB Expenses	54,000
Reduction of Other Post-Retirement Regulatory Liability	$ (18,500)