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Pension Benefits - Additional Information (Details) - Pension Benefits - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items] |  |
Estimated future employer contributions |  | $ 467
CECONY |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Estimated future employer contributions |  | $ 429
Contributions | $ 4 |

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