Regulatory Matters [Line Items]

Reduction to annual revenue requirement for actuarial projections of pension and other-post retirement benefit income expected to be recognized

$ 14.0

Regulatory Matters [Line Items]

Approved return on equity (as a percent)

9.70%

Additional increase in annual revenue requirement in third year

$ 12.7

Public utilities authorized rate increase, amount

$ 23.0

Public utilities, requested OPEB surcredit for customer refund

$ 7.2

Public utilities distribution system improvement charge recovered from customers

$ 2.8

Regulatory Matters [Line Items]

FERC requested annual cost of service

$ 404.0

Regulatory Matters (Details) - USD ($) $ in Millions				3 Months Ended	12 Months Ended			36 Months Ended
Regulatory Matters (Details) - USD ($) $ in Millions	Apr. 30, 2026	Jan. 28, 2026	Aug. 01, 2023	Mar. 31, 2026	Sep. 30, 2027	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2027	Nov. 01, 2025	Dec. 05, 2024
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
Requested base rate increase		$ 19.7
Public utilities, requested OPEB surcredit for customer refund		$ 7.2
Public utilities, cap equivalent to distribution revenues, percentage										5.00%
Public utilities distribution system improvement charge recovered from customers				$ 2.8
Empire
Regulatory Matters [Line Items]
FERC estimated annual reduction of revenue amount									$ 0.5
Supply Corporation \| Subsequent Event
Regulatory Matters [Line Items]
FERC requested annual cost of service	$ 404.0
FERC requested increase in settlement from rate proceeding	$ 95.0