Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 4,608	$ 4,381
Regulatory liabilities – current	555	185
Total Regulatory Liabilities	5,163	4,566
Regulatory assets	3,659	3,639
MTA power reliability deferral
Regulatory Liabilities [Line Items]
Regulatory assets	116	140
Gas Service Line Deferred Costs
Regulatory Liabilities [Line Items]
Regulatory assets	108	100
Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,110	3,921
Regulatory liabilities – current	463	134
Regulatory assets	3,336	3,316
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,868	1,984
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,223	1,199
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	346	32
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	157	209
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	120	102
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	129	61
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	86	103
TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	62	125
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	69	70
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	29	17
BQDM and REV Demo reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24	25
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	13
Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	9	12
Workers' compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	8
Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	5	15
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	6
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	417	365
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	491	142
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	46	32
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	18	11
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,110	3,921
Regulatory liabilities – current	463	134
Total Regulatory Liabilities	4,573	4,055
Regulatory assets	3,336	3,316
CECONY | Subsidiaries | MTA power reliability deferral
Regulatory Liabilities [Line Items]
Regulatory assets	116	140
CECONY | Subsidiaries | Gas Service Line Deferred Costs
Regulatory Liabilities [Line Items]
Regulatory assets	108	100
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,729	1,840
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,051	1,033
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	283	0
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	157	209
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	75	55
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	117	55
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	86	103
CECONY | TCJA net benefits | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	60	123
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	66	63
CECONY | Property tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
CECONY | Sales and use tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	28	16
CECONY | BQDM and REV Demo reconciliations | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	21	22
CECONY | Earnings sharing - electric, gas and steam | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	10
CECONY | Settlement of gas proceedings | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	9	12
CECONY | Workers' compensation | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	8
CECONY | Energy efficiency portfolio standard unencumbered funds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	7	19
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	6
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	360	312
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	451	132
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	12	2
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 0	$ 0