Capitalization - Carrying Amounts and Fair Values of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Long-term debt (including current portion)	$ 24,909	$ 24,651
Unamortized debt expense	241	249
Carrying Amount
Debt Instrument [Line Items]
Long-term debt (including current portion)	24,909	24,651
Fair Value
Debt Instrument [Line Items]
Long-term debt (including current portion)	22,995	21,997
CECONY
Debt Instrument [Line Items]
Long-term debt (including current portion)	23,418	23,409
CECONY | Subsidiaries
Debt Instrument [Line Items]
Unamortized debt discount	232	241
CECONY | Carrying Amount | Subsidiaries
Debt Instrument [Line Items]
Long-term debt (including current portion)	23,418	23,409
CECONY | Fair Value | Subsidiaries
Debt Instrument [Line Items]
Long-term debt (including current portion)	$ 21,640	20,915
Broken Bow II | Carrying Amount
Debt Instrument [Line Items]
Long-term debt (including current portion)		$ 59