Regulatory Matters - Summary of Utilities Rate Plans (CECONY-Electric) (Details) - CECONY - Electric - Scenario, Forecast $ in Thousands	36 Months Ended
	Dec. 31, 2028 USD ($)
Public Utilities, General Disclosures [Line Items]
Retention of annual transmission congestion revenues	$ 75,000
Authorized return on common equity (percent)	9.40%
Earnings sharing (percent)	9.90%
Common equity ratio (percent)	48.00%
Electric base rate percentage	2.80%
Recovery deferral (percent)	80.00%
Maximum deferral (percent)	15.00%
Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes	$ 222,000
Capital expenditures	4,550,000
Amortizations to income of net liabilities	88,000
Potential earnings adjustment mechanism incentives	40,000
Potential charges	653,000
Average rate base	$ 32,935,000
Weighted average cost of capital (after-tax) (percent)	6.98%
Cost of long-term debt (percent)	4.78%
Requested rate increase, amount	$ 234,000
Year 1 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations	33,590,000
Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes	473,000
Capital expenditures	4,474,000
Amortizations to income of net liabilities	81,000
Potential earnings adjustment mechanism incentives	42,000
Potential charges	688,000
Average rate base	$ 35,149,000
Weighted average cost of capital (after-tax) (percent)	7.04%
Cost of long-term debt (percent)	4.90%
Requested rate increase, amount	$ 410,000
Year 2 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations	35,186,000
Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes	329,000
Capital expenditures	4,712,000
Amortizations to income of net liabilities	78,000
Potential earnings adjustment mechanism incentives	47,000
Potential charges	745,000
Average rate base	$ 39,174,000
Weighted average cost of capital (after-tax) (percent)	7.10%
Cost of long-term debt (percent)	5.01%
Requested rate increase, amount	$ 421,000
Year 3 | Electric average excluding AMI
Public Utilities, General Disclosures [Line Items]
Net utility plant reconciliations	38,624,000
Protected Portion | Year 1
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	63,000
Actual net expenses amount	8,500
Protected Portion | Year 2
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	58,000
Actual net expenses amount	12,750
Protected Portion | Year 3
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	55,000
Actual net expenses amount	17,000
Unprotected Portion | Year 1
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	24,000
Impact in regulatory liability resulting from TCJA	1,000
Unprotected Portion | Year 2
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	22,000
Impact in regulatory liability resulting from TCJA	1,000
Unprotected Portion | Year 3
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	22,000
Impact in regulatory liability resulting from TCJA	$ 1,000