Regulatory Matters - Summary of Utilities Rate Plans (CECONY-Gas) (Details) - CECONY - Gas - Scenario, Forecast $ in Thousands	36 Months Ended
	Dec. 31, 2028 USD ($)
Public Utilities, General Disclosures [Line Items]
Percentage of revenue reserve	15.00%
Earnings sharing (percent)	9.90%
Common equity ratio (percent)	48.00%
Annual gas revenue requirement	$ 33,330
Recovery deferral (percent)	80.00%
Maximum deferral (percent)	15.00%
Maximum
Public Utilities, General Disclosures [Line Items]
Amount of revenues retained	$ 65,000
Year 1
Public Utilities, General Disclosures [Line Items]
Base rate changes	(46,000)
Capital expenditures	1,093,000
Amortizations to income of net liabilities	90,000
Potential charges	133,000
Net utility plant reconciliations	12,931,000
Average rate base	$ 11,485,000
Weighted average cost of capital (after-tax) (percent)	6.98%
Authorized return on common equity (percent)	9.40%
Cost of long-term debt (percent)	4.78%
Electric base rate percentage	2.01%
Requested rate increase, amount	$ 28,000
Actual net expenses amount	1,500
Potential offsetting credit adjustments	12,000
Year 2
Public Utilities, General Disclosures [Line Items]
Base rate changes	170,000
Capital expenditures	1,057,000
Amortizations to income of net liabilities	88,000
Potential charges	140,000
Net utility plant reconciliations	13,472,000
Average rate base	$ 12,050,000
Weighted average cost of capital (after-tax) (percent)	7.04%
Cost of long-term debt (percent)	4.90%
Requested rate increase, amount	$ 69,000
Actual net expenses amount	2,250
Potential offsetting credit adjustments	13,000
Year 3
Public Utilities, General Disclosures [Line Items]
Base rate changes	93,000
Capital expenditures	1,065,000
Amortizations to income of net liabilities	86,000
Potential charges	149,000
Net utility plant reconciliations	14,014,000
Average rate base	$ 12,615,000
Weighted average cost of capital (after-tax) (percent)	7.10%
Cost of long-term debt (percent)	5.01%
Requested rate increase, amount	$ 70,000
Actual net expenses amount	3,000
Potential offsetting credit adjustments	14,000
Over Three Years
Public Utilities, General Disclosures [Line Items]
Annual gas revenue requirement	100,000
Protected Portion | Year 1
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	48,000
Protected Portion | Year 2
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	46,000
Protected Portion | Year 3
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	45,000
Unprotected Portion | Year 1
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	6,000
Impact in regulatory liability resulting from TCJA	36,000
Unprotected Portion | Year 2
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	6,000
Impact in regulatory liability resulting from TCJA	36,000
Unprotected Portion | Year 3
Public Utilities, General Disclosures [Line Items]
Reflects regulatory liability amortization	5,000
Impact in regulatory liability resulting from TCJA	$ 36,000