Regulatory Matters - Summary of Utilities Rate Plans (O&R New York-Electric) (Details) - USD ($) $ in Millions	36 Months Ended
	Dec. 31, 2024	Sep. 30, 2021
NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues		15.00%
Percentage of debt to total consolidated debt		20.00%
O&R | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Authorized return on common equity (percent)	9.20%
Earnings sharing (percent)	9.70%
Common equity ratio (percent)	48.00%
Deferrals for property taxes limitation from rates (percent)	90.00%
O&R | Electric | Scenario, Forecast | Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes	$ 4.9
Amortization to income of net regulatory assets	11.8
Potential earnings adjustment mechanism incentives	3.3
Net utility plant reconciliations	1,175.0
Average rate base	$ 1,021.0
Weighted average cost of capital (after-tax) (percent)	6.77%
Cost of long-term debt (percent)	4.58%
Requested rate increase (decrease), amount	$ 11.7
Regulatory Asset, Amortization Period	5 years
Deferral, annual maximum (not more than) (percent)	0.10%
O&R | Electric | Scenario, Forecast | Year 1 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)	$ 4.3
O&R | Electric | Scenario, Forecast | Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes	16.2
Amortization to income of net regulatory assets	13.5
Potential earnings adjustment mechanism incentives	2.3
Net utility plant reconciliations	1,198.0
Average rate base	$ 1,044.0
Weighted average cost of capital (after-tax) (percent)	6.73%
Cost of long-term debt (percent)	4.51%
Requested rate increase (decrease), amount	$ 11.7
Deferral, annual maximum (not more than) (percent)	0.075%
O&R | Electric | Scenario, Forecast | Year 2 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)	$ 4.4
O&R | Electric | Scenario, Forecast | Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes	23.1
Amortization to income of net regulatory assets	15.2
Potential earnings adjustment mechanism incentives	4.0
Net utility plant reconciliations	1,304.0
Average rate base	$ 1,144.0
Weighted average cost of capital (after-tax) (percent)	6.72%
Cost of long-term debt (percent)	4.49%
Requested rate increase (decrease), amount	$ 11.7
Deferral, annual maximum (not more than) (percent)	0.05%
O&R | Electric | Scenario, Forecast | Year 3 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)	$ 5.1