Capitalization - Carrying Amounts and Fair Values of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	$ 14,862	$ 14,774
Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	16,206	16,093
CECONY | Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	12,075	12,073
CECONY | Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	$ 13,288	$ 13,268