Schedule I - Condensed Financial Information - Condensed Statement of Income and Comprehensive Income (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Income Statements,Captions [Line Items]
Interest expense	$ (696)	$ (653)	$ (591)
NET INCOME	1,245	1,193	1,092
Comprehensive Income	$ 1,252	$ 1,204	$ 1,072
Net Income Per Share – Basic (dollars per share)	$ 4.15	$ 4.07	$ 3.73
Net Income Per Share – Diluted (dollars per share)	4.12	4.05	3.71
Dividends Declared Per Share (dollars per share)	$ 2.68	$ 2.60	$ 2.52
Average Number Of Shares Outstanding—Basic (In Millions)	300.4	293.0	292.9
Average Number Of Shares Outstanding—Diluted (In Millions)	301.9	294.4	294.0
Consolidated Edison, Inc.
Condensed Income Statements,Captions [Line Items]
Equity in earnings of subsidiaries	$ 1,254	$ 1,195	$ 1,101
Other income (deductions), net of taxes	32	27	19
Interest expense	(41)	(29)	(28)
NET INCOME	1,245	1,193	1,092
Comprehensive Income	$ 1,252	$ 1,204	$ 1,072
Net Income Per Share – Basic (dollars per share)	$ 4.15	$ 4.07	$ 3.73
Net Income Per Share – Diluted (dollars per share)	4.12	4.05	3.71
Dividends Declared Per Share (dollars per share)	$ 2.68	$ 2.60	$ 2.52
Average Number Of Shares Outstanding—Basic (In Millions)	300.4	293.0	292.9
Average Number Of Shares Outstanding—Diluted (In Millions)	301.9	294.4	294.0