Schedule I - Condensed Financial Information - Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	$ 1,382	$ 1,525	$ 1,245
Change in Assets:
Taxes receivable	27	15	87
Other – net	(62)	0	69
NET CASH FLOWS FROM OPERATING ACTIVITIES	2,695	3,367	3,459
INVESTING ACTIVITIES
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(5,471)	(3,710)	(4,950)
FINANCING ACTIVITIES
Net proceeds of short-term debt	1,989	(477)	(475)
Issuance of long-term debt	3,030	1,697	2,590
Retirement of long-term debt	(1,938)	(434)	(735)
Debt issuance costs	(61)	(19)	(24)
Issuance of common shares for stock plans	53	51	51
Issuance of common shares - public offering	705	343	702
Common stock dividends	(842)	(803)	(763)
NET CASH FLOWS FROM FINANCING ACTIVITIES	2,938	357	1,345
BALANCE AT BEGINNING OF PERIOD	797
BALANCE AT END OF PERIOD EXCLUDING HELD FOR SALE	895	797
CECONY
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	1,196	1,104	1,056
Change in Assets:
Other – net	(96)	23	(11)
NET CASH FLOWS FROM OPERATING ACTIVITIES	2,204	2,866	3,038
INVESTING ACTIVITIES
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(3,306)	(3,080)	(2,753)
FINANCING ACTIVITIES
Net proceeds of short-term debt	1,042	(450)	(433)
Issuance of long-term debt	2,740	1,200	1,300
Retirement of long-term debt	(1,836)	0	(650)
Debt issuance costs	(30)	(15)	(13)
NET CASH FLOWS FROM FINANCING ACTIVITIES	1,190	240	(440)
BALANCE AT BEGINNING OF PERIOD	730
BALANCE AT END OF PERIOD EXCLUDING HELD FOR SALE	818	730
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net Income	1,382	1,525	1,245
Equity in earnings of subsidiaries	(1,447)	(1,544)	(1,254)
Change in Assets:
Special deposits	(8)	0	0
Taxes receivable	2	34	87
Other – net	187	21	(152)
NET CASH FLOWS FROM OPERATING ACTIVITIES	1,033	896	723
INVESTING ACTIVITIES
Contributions to subsidiaries	(1,110)	(434)	(691)
Debt receivable from affiliated companies	(825)	0	(900)
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(1,935)	(434)	(1,591)
FINANCING ACTIVITIES
Net proceeds of short-term debt	164	(53)	(53)
Issuance of long-term debt	825	400	900
Retirement of long-term debt	(3)	(402)	(2)
Debt issuance costs	0	(2)	(5)
Issuance of common shares for stock plans	53	51	51
Issuance of common shares - public offering	705	343	702
Common stock dividends	(842)	(803)	(763)
NET CASH FLOWS FROM FINANCING ACTIVITIES	902	(466)	830
NET CHANGE FOR THE PERIOD	0	(4)	(38)
BALANCE AT BEGINNING OF PERIOD	9	13	51
BALANCE AT END OF PERIOD EXCLUDING HELD FOR SALE	9	9	13
Parent Company | CECONY
Condensed Cash Flow Statements, Captions [Line Items]
Dividends received	846	796	744
Parent Company | O&R
Condensed Cash Flow Statements, Captions [Line Items]
Dividends received	46	44	43
Parent Company | Clean Energy Businesses
Condensed Cash Flow Statements, Captions [Line Items]
Dividends received	15	12	10
Parent Company | Con Edison Transmission
Condensed Cash Flow Statements, Captions [Line Items]
Dividends received	$ 10	$ 8	$ 0