Regulatory Matters - Narrative (Details) - USD ($) $ in Millions		12 Months Ended			36 Months Ended
	Aug. 01, 2023	Sep. 30, 2027	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2027	Nov. 01, 2025
New York
Regulatory Matters [Line Items]
Increase in annual revenue requirement in first year				$ 57.3
Reduction to annual revenue requirement for actuarial projections of pension and other-post retirement benefit income expected to be recognized				14.0
New York | Forecast
Regulatory Matters [Line Items]
Rate plan period					3 years
Approved return on equity (as a percent)					9.70%
Additional increase in annual revenue requirement in second year			$ 15.8
Additional increase in annual revenue requirement in third year		$ 12.7
Reduction to annual revenue requirement for actuarial projections of pension and other-post retirement benefit income expected to be recognized		$ 14.0	$ 14.0
Pennsylvania
Regulatory Matters [Line Items]
Public utilities authorized rate increase, amount	$ 23.0
Public utilities distribution system improvement charge recovered from customers				$ 0.9
Empire | Forecast
Regulatory Matters [Line Items]
FERC estimated annual reduction of revenue amount						$ 0.5