Capitalization - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jan. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019
Schedule of Capitalization [Line Items]
Number of shares of common stock issued	1,050,000
Value of common stock issued	$ 88,000,000	$ 0	$ 88,000,000	$ 400,000,000	$ 425,000,000
PG&E Project
Schedule of Capitalization [Line Items]
Short-term debt						$ 1,001,000,000
Long-term debt		$ 898,000,000
Debentures | 3.35% Debentures Due 2030 | CECONY
Schedule of Capitalization [Line Items]
Face amount of debt			$ 600,000,000
Interest rate			3.35%
Debentures | 3.95% Debentures Due 2050 | CECONY
Schedule of Capitalization [Line Items]
Face amount of debt			$ 1,000,000,000
Interest rate			3.95%