Income Tax	9 Months Ended
Income Tax	Sep. 30, 2015
Income Tax Examination [Line Items]
Income Tax	Income Tax Con Edison’s income tax expense decreased to $249 million for the three months ended September 30, 2015 from $259 million for the three months ended September 30, 2014. Con Edison's effective tax rate for the three months ended September 30, 2015 and 2014 was 37 percent. CECONY’s income tax expense decreased to $222 million for the three months ended September 30, 2015 from $233 million for the three months ended September 30, 2014. CECONY's effective tax rate for the three months ended September 30, 2015 and 2014 was 37 percent. Con Edison’s income tax expense decreased to $548 million for the nine months ended September 30, 2015 from $559 million for the nine months ended September 30, 2014. Con Edison's effective tax rate for the nine months ended September 30, 2015 and 2014 was 35 percent and 36 percent, respectively. The decrease in Con Edison’s effective tax rate is due primarily to higher production tax credits and amortization of investment tax credits from the competitive energy businesses. CECONY’s income tax expense increased to $515 million for the nine months ended September 30, 2015 from $496 million for the nine months ended September 30, 2014. CECONY's effective tax rate for the nine months ended September 30, 2015 and 2014 was 35 percent. In September 2015, Con Edison and subsidiaries filed its 2014 federal income tax return. As part of the filing, the company generated excess income tax credits (principally investment tax credits). The company plans to carryback a portion of the excess tax credits to the 2013 federal income tax return and request a tax refund of $30 million. Uncertain Tax Positions At September 30, 2015, the estimated liability for uncertain tax positions for Con Edison was $34 million ($2 million for CECONY). Con Edison reasonably expects to resolve approximately $25 million ($16 million, net of federal taxes) of its uncertain tax positions within the next twelve months, of which the entire amount, if recognized, would reduce Con Edison’s effective tax rate. The amount related to CECONY is approximately $2 million ($1 million, net of federal taxes), of which the entire amount, if recognized, would reduce CECONY’s effective tax rate. The total amount of unrecognized tax benefits, if recognized, that would reduce Con Edison’s effective tax rate is $34 million ($22 million, net of federal taxes). The companies recognize interest on liabilities for uncertain tax positions in interest expense and would recognize penalties, if any, in operating expenses in the companies’ consolidated income statements. In the three and nine months ended September 30, 2015, Con Edison recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in its consolidated income statements. At September 30, 2015 and December 31, 2014, Con Edison recognized an immaterial amount of accrued interest on its consolidated balance sheets.
CECONY
Income Tax Examination [Line Items]
Income Tax	Income Tax Con Edison’s income tax expense decreased to $249 million for the three months ended September 30, 2015 from $259 million for the three months ended September 30, 2014. Con Edison's effective tax rate for the three months ended September 30, 2015 and 2014 was 37 percent. CECONY’s income tax expense decreased to $222 million for the three months ended September 30, 2015 from $233 million for the three months ended September 30, 2014. CECONY's effective tax rate for the three months ended September 30, 2015 and 2014 was 37 percent. Con Edison’s income tax expense decreased to $548 million for the nine months ended September 30, 2015 from $559 million for the nine months ended September 30, 2014. Con Edison's effective tax rate for the nine months ended September 30, 2015 and 2014 was 35 percent and 36 percent, respectively. The decrease in Con Edison’s effective tax rate is due primarily to higher production tax credits and amortization of investment tax credits from the competitive energy businesses. CECONY’s income tax expense increased to $515 million for the nine months ended September 30, 2015 from $496 million for the nine months ended September 30, 2014. CECONY's effective tax rate for the nine months ended September 30, 2015 and 2014 was 35 percent. In September 2015, Con Edison and subsidiaries filed its 2014 federal income tax return. As part of the filing, the company generated excess income tax credits (principally investment tax credits). The company plans to carryback a portion of the excess tax credits to the 2013 federal income tax return and request a tax refund of $30 million. Uncertain Tax Positions At September 30, 2015, the estimated liability for uncertain tax positions for Con Edison was $34 million ($2 million for CECONY). Con Edison reasonably expects to resolve approximately $25 million ($16 million, net of federal taxes) of its uncertain tax positions within the next twelve months, of which the entire amount, if recognized, would reduce Con Edison’s effective tax rate. The amount related to CECONY is approximately $2 million ($1 million, net of federal taxes), of which the entire amount, if recognized, would reduce CECONY’s effective tax rate. The total amount of unrecognized tax benefits, if recognized, that would reduce Con Edison’s effective tax rate is $34 million ($22 million, net of federal taxes). The companies recognize interest on liabilities for uncertain tax positions in interest expense and would recognize penalties, if any, in operating expenses in the companies’ consolidated income statements. In the three and nine months ended September 30, 2015, Con Edison recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in its consolidated income statements. At September 30, 2015 and December 31, 2014, Con Edison recognized an immaterial amount of accrued interest on its consolidated balance sheets.