Short-Term Borrowing	12 Months Ended
Dec. 31, 2017
Debt Disclosure [Abstract]
Short-Term Borrowing	Short-Term Borrowing In December 2016, Con Edison and the Utilities entered into a credit agreement (Credit Agreement), under which banks are committed to provide loans and letters of credit on a revolving credit basis. The Credit Agreement expires in December 2022. There is a maximum of $2,250 million of credit available. The full amount is available to CECONY and $1,000 million (subject to increase up to $1,500 million) is available to Con Edison, including up to $1,200 million of letters of credit. The Credit Agreement supports the Companies’ commercial paper programs. The Companies have not borrowed under the Credit Agreement. At December 31, 2017, Con Edison had $577 million of commercial paper outstanding, of which $150 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2017 was 1.8 percent for both Con Edison and CECONY. At December 31, 2016, Con Edison had $1,054 million of commercial paper outstanding of which $600 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2016 was 1.0 percent for both Con Edison and CECONY. At December 31, 2017 and 2016, no loans were outstanding under the credit agreement (Credit Agreement). An immaterial amount and $2 million (including $2 million for CECONY) of letters of credit were outstanding under the Credit Agreement as of December 31, 2017 and 2016, respectively. The banks’ commitments under the Credit Agreement are subject to certain conditions, including that there be no event of default. The commitments are not subject to maintenance of credit rating levels or the absence of a material adverse change. Upon a change of control of, or upon an event of default by one of the Companies, the banks may terminate their commitments with respect to that company, declare any amounts owed by that company under the Credit Agreement immediately due and payable and require that company to provide cash collateral relating to the letters of credit issued for it under the Credit Agreement. Events of default include the exceeding at any time of a ratio of consolidated debt to consolidated total capital of 0.65 to 1 (at December 31, 2017 this ratio was 0.51 to 1 for Con Edison and 0.52 to 1 for CECONY); having liens on its assets in an aggregate amount exceeding five percent of its consolidated total capital, subject to certain exceptions; and the failure, following any applicable notice period, to meet certain other customary covenants. Interest and fees charged for the revolving credit facilities and any loans made or letters of credit issued under the Credit Agreement reflect the Companies’ respective credit ratings. The Companies were in compliance with their covenants at December 31, 2017. See Note S for information about short-term borrowing between related parties.

Short-Term Borrowing

In December 2016, Con Edison and the Utilities entered into a credit agreement (Credit Agreement), under which banks are committed to provide loans and letters of credit on a revolving credit basis. The Credit Agreement expires in December 2022. There is a maximum of $2,250 million of credit available. The full amount is available to CECONY and $1,000 million (subject to increase up to $1,500 million) is available to Con Edison, including up to $1,200 million of letters of credit. The Credit Agreement supports the Companies’ commercial paper programs. The Companies have not borrowed under the Credit Agreement. At December 31, 2017, Con Edison had $577 million of commercial paper outstanding, of which $150 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2017 was 1.8 percent for both Con Edison and CECONY. At December 31, 2016, Con Edison had $1,054 million of commercial paper outstanding of which $600 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2016 was 1.0 percent for both Con Edison and CECONY.

At December 31, 2017 and 2016, no loans were outstanding under the credit agreement (Credit Agreement). An immaterial amount and $2 million (including $2 million for CECONY) of letters of credit were outstanding under the Credit Agreement as of December 31, 2017 and 2016, respectively.

The banks’ commitments under the Credit Agreement are subject to certain conditions, including that there be no event of default. The commitments are not subject to maintenance of credit rating levels or the absence of a material adverse change. Upon a change of control of, or upon an event of default by one of the Companies, the banks may terminate their commitments with respect to that company, declare any amounts owed by that company under the Credit Agreement immediately due and payable and require that company to provide cash collateral relating to the letters of credit issued for it under the Credit Agreement. Events of default include the exceeding at any time of a ratio of consolidated debt to consolidated total capital of 0.65 to 1 (at December 31, 2017 this ratio was 0.51 to 1 for Con Edison and 0.52 to 1 for CECONY); having liens on its assets in an aggregate amount exceeding five percent of its consolidated total capital, subject to certain exceptions; and the failure, following any applicable notice period, to meet certain other customary covenants. Interest and fees charged for the revolving credit facilities and any loans made or letters of credit issued under the Credit Agreement reflect the Companies’ respective credit ratings. The Companies were in compliance with their covenants at December 31, 2017.

See Note S for information about short-term borrowing between related parties.