Income Tax	3 Months Ended
Income Tax	Mar. 31, 2016
Income Tax Examination [Line Items]
Income Tax	Income Tax Con Edison’s income tax expense decreased to $164 million for the three months ended March 31, 2016 from $199 million for the three months ended March 31, 2015. Con Edison's effective tax rate for the three months ended March 31, 2016 and 2015 was 35 percent. For the three months ended March 31, 2016, Con Edison recorded income tax benefits for research and development tax credits, which were primarily offset by a decrease in tax benefits for plant-related flow through items due to a change in regulatory accounting. CECONY’s income tax expense decreased to $180 million for the three months ended March 31, 2016 from $192 million for the three months ended March 31, 2015. CECONY's effective tax rate for the three months ended March 31, 2016 and 2015 was 37 percent and 36 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 due to a change in regulatory accounting, partially offset by research and development tax credits. Con Edison anticipates a federal consolidated net operating loss for 2016, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2016 net operating loss to 2014 and recover $10 million of income tax. General business tax credits that became available as a result of the net operating loss carryback to 2014, 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 were 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 March 31, 2016, the estimated liability for uncertain tax positions for Con Edison was $36 million ($4 million for CECONY). Con Edison reasonably expects to resolve approximately $27 million ($18 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 $4 million ($3 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 $36 million ($24 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 months ended March 31, 2016, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At March 31, 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 decreased to $164 million for the three months ended March 31, 2016 from $199 million for the three months ended March 31, 2015. Con Edison's effective tax rate for the three months ended March 31, 2016 and 2015 was 35 percent. For the three months ended March 31, 2016, Con Edison recorded income tax benefits for research and development tax credits, which were primarily offset by a decrease in tax benefits for plant-related flow through items due to a change in regulatory accounting. CECONY’s income tax expense decreased to $180 million for the three months ended March 31, 2016 from $192 million for the three months ended March 31, 2015. CECONY's effective tax rate for the three months ended March 31, 2016 and 2015 was 37 percent and 36 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 due to a change in regulatory accounting, partially offset by research and development tax credits. Con Edison anticipates a federal consolidated net operating loss for 2016, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2016 net operating loss to 2014 and recover $10 million of income tax. General business tax credits that became available as a result of the net operating loss carryback to 2014, 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 were 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 March 31, 2016, the estimated liability for uncertain tax positions for Con Edison was $36 million ($4 million for CECONY). Con Edison reasonably expects to resolve approximately $27 million ($18 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 $4 million ($3 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 $36 million ($24 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 months ended March 31, 2016, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At March 31, 2016 and December 31, 2015, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.