Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 4,381	$ 4,513
Regulatory liabilities—current	185	36
Total Regulatory Liabilities	4,566	4,549
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,984	2,207
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,199	1,090
TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	125	295
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	209	198
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	103	137
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	102	85
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	70	64
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	61	5
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	36
BQDM and REV Demo reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	25	27
Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	12	21
Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	17	16
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	15
Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	32	11
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	5
Workers’ compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8	3
Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	1
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	365	297
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	32	28
Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	142	8
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	11	0
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	3,921	4,094
Regulatory liabilities—current	134	11
Total Regulatory Liabilities	4,055	4,105
CECONY | Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,840	2,062
CECONY | Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,033	932
CECONY | TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	123	286
CECONY | Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	209	198
CECONY | Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	103	137
CECONY | Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	55	46
CECONY | System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	63	57
CECONY | Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	55	4
CECONY | Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
CECONY | BQDM and REV Demo reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	22	25
CECONY | Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	12	21
CECONY | Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	16	16
CECONY | Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	10
CECONY | Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	0	0
CECONY | Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	5
CECONY | Workers’ compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8	3
CECONY | Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	0
CECONY | Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	312	257
CECONY | Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	2	4
CECONY | Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	132	7
CECONY | Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	$ 0	$ 0