Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 4,717	$ 4,381
Regulatory liabilities – current	568	185
Total Regulatory Liabilities	5,285	4,566
Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,215	3,921
Regulatory liabilities – current	486	134
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,819	1,984
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,238	1,199
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	429	32
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	126	209
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	152	61
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	130	102
2022 Late Payment Charge Deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	92	0
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	78	103
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	72	70
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	37	35
TCJA net benefits
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	30	125
Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	28	17
BQDM and REV Demo reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24	25
COVID-19 pandemic uncollectible reconciliation deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	20	0
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	13
Workers' compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	11	8
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	6
Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	5	15
Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4	12
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	403	365
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	521	142
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	34	32
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	13	11
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,215	3,921
Regulatory liabilities – current	486	134
Total Regulatory Liabilities	4,701	4,055
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,681	1,840
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,063	1,033
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	368	0
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	126	209
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	134	55
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	85	55
CECONY | 2022 Late Payment Charge Deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	92	0
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	77	103
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	67	63
CECONY | Property tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
CECONY | TCJA net benefits | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	29	123
CECONY | Sales and use tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	27	16
CECONY | BQDM and REV Demo reconciliations | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	21	22
CECONY | COVID-19 pandemic uncollectible reconciliation deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	0
CECONY | Earnings sharing - electric, gas and steam | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	10
CECONY | Workers' compensation | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	11	8
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6	6
CECONY | Energy efficiency portfolio standard unencumbered funds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	7	19
CECONY | Settlement of gas proceedings | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4	12
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	353	312
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	482	132
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	4	2
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 0	$ 0