Regulatory Matters - Summary of Utilities Rate Plans (O&R New York-Electric) (Details) - USD ($)	12 Months Ended				36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2024	Dec. 31, 2021
Public Utilities, General Disclosures [Line Items]
Deferred regulatory assets	$ 702,000,000	$ 662,000,000				$ 662,000,000
Deferred regulatory liabilities	$ 3,000,000	7,000,000	$ 41,000,000	$ 17,000,000		7,000,000
NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues	15.00%
Percentage of debt to total consolidated debt	20.00%
Maximum | NYSPSC
Public Utilities, General Disclosures [Line Items]
Percentage of total consolidated revenues	15.00%
O&R | Electric
Public Utilities, General Disclosures [Line Items]
Deferred regulatory assets			6,000,000	100,000
Deferred regulatory liabilities	$ 6,900,000	10,000,000				10,000,000
Negative revenue adjustments		0	0	0
Deferral of net increase (decrease) to regulatory assets	$ 9,400,000	24,000,000	30,300,000	$ 4,300,000
Deferred regulatory asset (liability)		(400,000)				$ (400,000)
Earnings sharing (percent)				9.60%
Common equity ratio (percent)						48.00%
Recovery of late payment charges, period (in years)	3 years
Recovery of late payment charges, amount	$ 2,200,000
Recovery of late payment charges, return on equity threshold rate	500.00%
Deferrals for property taxes limitation from rates (percent)						90.00%
O&R | Electric | Rate Plan for Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes						$ 13,400,000
Amortization to income of net regulatory assets						1,500,000
Potential earnings adjustment mechanism incentives						3,600,000
Potential incentive if target is met, related to service terminations						500,000
Average rate base						$ 878,000,000
Weighted average cost of capital (after-tax) (percent)						6.97%
Authorized return on common equity (percent)						9.00%
Actual return on common equity (percent)						9.60%
Cost of long-term debt (percent)						5.17%
Regulatory assets, amortization period (in years)						6 years
Requested rate increase (decrease), amount						$ 8,600,000
Deferral, annual maximum (not more than) (percent)						0.10%
O&R | Electric | Rate Plan for Year 1 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						$ 1,008,000,000
O&R | Electric | Rate Plan for Year 1 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						48,000,000
O&R | Electric | Rate Plan for Year 1 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)						4,400,000
O&R | Electric | Rate Plan for Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes						8,000,000
Amortization to income of net regulatory assets						1,500,000
Potential earnings adjustment mechanism incentives						4,000,000
Potential incentive if target is met, related to service terminations						500,000
Average rate base						$ 906,000,000
Weighted average cost of capital (after-tax) (percent)						6.96%
Actual return on common equity (percent)						8.76%
Cost of long-term debt (percent)						5.14%
Requested rate increase (decrease), amount						$ 12,100,000
Deferral, annual maximum (not more than) (percent)						0.075%
O&R | Electric | Rate Plan for Year 2 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						$ 1,032,000,000
O&R | Electric | Rate Plan for Year 2 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						58,000,000
O&R | Electric | Rate Plan for Year 2 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)						4,400,000
O&R | Electric | Rate Plan for Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes						5,800,000
Amortization to income of net regulatory assets						1,500,000
Potential earnings adjustment mechanism incentives						4,200,000
Potential incentive if target is met, related to service terminations	$ 2,700,000					500,000
Average rate base						$ 948,000,000
Weighted average cost of capital (after-tax) (percent)						6.96%
Actual return on common equity (percent)						9.16%
Cost of long-term debt (percent)						5.14%
Requested rate increase (decrease), amount						$ 12,200,000
Deferral, annual maximum (not more than) (percent)						0.05%
O&R | Electric | Rate Plan for Year 3 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						$ 1,083,000,000
O&R | Electric | Rate Plan for Year 3 | Advanced metering infrastructure (AMI)
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations						61,000,000
O&R | Electric | Rate Plan for Year 3 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)						$ 4,500,000
O&R | Electric | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Actual return on common equity (percent)					0.0009%
Earnings sharing (percent)					9.70%
Common equity ratio (percent)					48.00%
O&R | Electric | Scenario, Forecast | Rate Plan for Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes					$ 4,900,000
Amortization to income of net regulatory assets					11,800,000
Potential earnings adjustment mechanism incentives					3,300,000
Average rate base					$ 1,021,000,000
Weighted average cost of capital (after-tax) (percent)					6.77%
Authorized return on common equity (percent)					9.20%
Cost of long-term debt (percent)					4.58%
Regulatory assets, amortization period (in years)					5 years
Requested rate increase (decrease), amount					$ 11,700,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 1 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations					1,175,000,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 1 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)					4,300,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes					16,200,000
Amortization to income of net regulatory assets					13,500,000
Potential earnings adjustment mechanism incentives					2,300,000
Average rate base					$ 1,044,000,000
Weighted average cost of capital (after-tax) (percent)					6.73%
Cost of long-term debt (percent)					4.51%
Requested rate increase (decrease), amount					$ 11,700,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 2 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations					1,198,000,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 2 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)					4,400,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes					23,100,000
Amortization to income of net regulatory assets					15,200,000
Potential earnings adjustment mechanism incentives					4,000,000
Average rate base					$ 1,144,000,000
Weighted average cost of capital (after-tax) (percent)					6.72%
Cost of long-term debt (percent)					4.49%
Requested rate increase (decrease), amount					$ 11,700,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 3 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations					1,304,000,000
O&R | Electric | Scenario, Forecast | Rate Plan for Year 3 | Maximum
Public Utilities, General Disclosures [Line Items]
Potential penalties (annually)					$ 5,100,000
Energy Efficiency | O&R | Electric
Public Utilities, General Disclosures [Line Items]
Actual earnings adjustment mechanism incentives		1,800,000	1,900,000	$ 2,600,000
Service Termination | O&R | Electric
Public Utilities, General Disclosures [Line Items]
Actual earnings adjustment mechanism incentives		0	$ 500,000	$ 200,000
Incentives reversed		$ 500,000