Environmental Matters - Additional Information (Details) - USD ($) $ in Billions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
CECONY | Asbestos Proceedings
Site Contingency [Line Items]
Estimated undiscounted asbestos liability (years)	15 years
Superfund Sites | Manufactured Gas Plant Sites | Maximum
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)		$ 2.7
Superfund Sites | Manufactured Gas Plant Sites | Maximum | CECONY
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)		$ 2.6