Pension Benefits - Additional Information (Details) - Pension Benefits $ in Millions	9 Months Ended
Sep. 30, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	$ 467
Contributions	465
CECONY \| Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	429
Contributions	428
CECONY \| Nonqualified Plan \| Subsidiaries
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 22

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration