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Derivative Instruments and Hedging Activities - Additional Information (Details) $ in Millions | 3 Months Ended
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Mar. 31, 2021 USD ($)
Investment Holdings [Line Items] |
Energy supply and hedging activities credit exposure total | $ 208
Makeup of net credit exposure non-investment grade/non-rated counterparties | 62
Makeup of net credit exposure independent system operators | 95
Makeup of net credit exposure with investment-grade counterparties | 20
Makeup of net credit exposure with commodity exchange brokers | 31
CECONY |
Investment Holdings [Line Items] |
Energy supply and hedging activities credit exposure total | 20
Makeup of net credit exposure with investment-grade counterparties | 4
Makeup of net credit exposure with commodity exchange brokers | $ 16

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