Income Tax	9 Months Ended
Income Tax	Sep. 30, 2016
Income Tax Examination [Line Items]
Income Tax	Income Tax Con Edison’s income tax expense increased to $314 million for the three months ended September 30, 2016 from $249 million for the three months ended September 30, 2015. Con Edison's effective tax rate for the three months ended September 30, 2016 and 2015 was 39 percent and 37 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to higher state income taxes and a decrease in tax benefits for plant-related flow through items, offset in part by higher tax benefits for injuries and damages payments, research and development tax credits and renewable energy tax credits. CECONY’s income tax expense increased to $226 million for the three months ended September 30, 2016 from $222 million for the three months ended September 30, 2015. CECONY's effective tax rate for the three months ended September 30, 2016 and 2015 was 37 percent. The decrease in tax benefits for plant-related flow through items, were more than offset by lower state income taxes and increased tax benefits as a result of higher injuries and damages payments and research and development tax credits. Con Edison’s income tax expense increased to $602 million for the nine months ended September 30, 2016 from $548 million for the nine months ended September 30, 2015. Con Edison's effective tax rate for the nine months ended September 30, 2016 and 2015 was 37 percent and 35 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to higher state income taxes and a decrease in tax benefits for plant-related flow through items, offset in part by higher tax benefits for injuries and damages payments, research and development tax credits and renewable energy tax credits. CECONY’s income tax expense decreased to $491 million for the nine months ended September 30, 2016 from $515 million for the nine months ended September 30, 2015. CECONY's effective tax rate for the nine months ended September 30, 2016 and 2015 was 36 percent and 35 percent, respectively. The increase in CECONY's effective tax rate is primarily related to a decrease in tax benefits for plant-related flow through items, offset in part by lower state income taxes and increased research and development tax credits. In September 2016, Con Edison filed its 2015 federal income tax return, requesting a refund of $19 million of estimated tax payments and, in October 2016, the company received the refund. The company carried back a 2015 net operating loss to 2007, requesting a refund of $16 million of federal income tax and, in October 2016, the company received the refund. Con Edison anticipates a federal net operating loss for 2016, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2016 net operating loss and recover $32 million of income tax. General business tax credits that became available as a result of the net operating loss carryback, as well as the remaining 2016 net operating loss will be carried forward to future tax years. A deferred tax asset for these tax attribute carryforwards was recorded, and no valuation allowance has been provided, as it is more likely than not that the deferred tax asset will be realized. Uncertain Tax Positions At September 30, 2016, the estimated liability for uncertain tax positions for Con Edison was $37 million ($5 million for CECONY). Con Edison reasonably expects to resolve approximately $29 million ($20 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 $5 million ($4 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 $37 million ($25 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, 2016, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At September 30, 2016 and December 31, 2015, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.
CECONY
Income Tax Examination [Line Items]
Income Tax	Income Tax Con Edison’s income tax expense increased to $314 million for the three months ended September 30, 2016 from $249 million for the three months ended September 30, 2015. Con Edison's effective tax rate for the three months ended September 30, 2016 and 2015 was 39 percent and 37 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to higher state income taxes and a decrease in tax benefits for plant-related flow through items, offset in part by higher tax benefits for injuries and damages payments, research and development tax credits and renewable energy tax credits. CECONY’s income tax expense increased to $226 million for the three months ended September 30, 2016 from $222 million for the three months ended September 30, 2015. CECONY's effective tax rate for the three months ended September 30, 2016 and 2015 was 37 percent. The decrease in tax benefits for plant-related flow through items, were more than offset by lower state income taxes and increased tax benefits as a result of higher injuries and damages payments and research and development tax credits. Con Edison’s income tax expense increased to $602 million for the nine months ended September 30, 2016 from $548 million for the nine months ended September 30, 2015. Con Edison's effective tax rate for the nine months ended September 30, 2016 and 2015 was 37 percent and 35 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to higher state income taxes and a decrease in tax benefits for plant-related flow through items, offset in part by higher tax benefits for injuries and damages payments, research and development tax credits and renewable energy tax credits. CECONY’s income tax expense decreased to $491 million for the nine months ended September 30, 2016 from $515 million for the nine months ended September 30, 2015. CECONY's effective tax rate for the nine months ended September 30, 2016 and 2015 was 36 percent and 35 percent, respectively. The increase in CECONY's effective tax rate is primarily related to a decrease in tax benefits for plant-related flow through items, offset in part by lower state income taxes and increased research and development tax credits. In September 2016, Con Edison filed its 2015 federal income tax return, requesting a refund of $19 million of estimated tax payments and, in October 2016, the company received the refund. The company carried back a 2015 net operating loss to 2007, requesting a refund of $16 million of federal income tax and, in October 2016, the company received the refund. Con Edison anticipates a federal net operating loss for 2016, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2016 net operating loss and recover $32 million of income tax. General business tax credits that became available as a result of the net operating loss carryback, as well as the remaining 2016 net operating loss will be carried forward to future tax years. A deferred tax asset for these tax attribute carryforwards was recorded, and no valuation allowance has been provided, as it is more likely than not that the deferred tax asset will be realized. Uncertain Tax Positions At September 30, 2016, the estimated liability for uncertain tax positions for Con Edison was $37 million ($5 million for CECONY). Con Edison reasonably expects to resolve approximately $29 million ($20 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 $5 million ($4 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 $37 million ($25 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, 2016, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At September 30, 2016 and December 31, 2015, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.