Income Tax	3 Months Ended
Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Tax	Income Tax Con Edison’s income tax expense increased to $227 million for the three months ended March 31, 2017 from $164 million for the three months ended March 31, 2016. Con Edison's effective tax rate for the three months ended March 31, 2017 and 2016 was 37 percent and 35 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and research and development tax credits, offset in part by lower state income taxes. CECONY’s income tax expense increased to $218 million for the three months ended March 31, 2017 from $180 million for the three months ended March 31, 2016. CECONY's effective tax rate for the three months ended March 31, 2017 and 2016 was 39 percent and 37 percent, respectively. The increase in CECONY's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and research and development tax credits, offset in part by lower state income taxes. Con Edison anticipates a federal consolidated net operating loss for 2017, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2017 net operating loss to recover $22 million of income tax and the remaining 2017 net operating loss, as well as general business tax credits generated in 2017, 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 March 31, 2017, the estimated liability for uncertain tax positions for Con Edison was $40 million ($21 million for CECONY). Con Edison reasonably expects to resolve approximately $33 million ($23 million, net of federal taxes) of its uncertain tax positions within the next twelve months, including $19 million ($13 million, net of federal taxes), which, if recognized, would reduce Con Edison’s effective tax rate. The amount related to CECONY is approximately $17 million ($12 million, net of federal taxes), including $2 million, which, 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 $23 million ($16 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, 2017, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At March 31, 2017 and December 31, 2016, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.

Income Tax

Con Edison’s income tax expense increased to $227 million for the three months ended March 31, 2017 from $164 million for the three months ended March 31, 2016. Con Edison's effective tax rate for the three months ended March 31, 2017 and 2016 was 37 percent and 35 percent, respectively. The increase in Con Edison's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and research and development tax credits, offset in part by lower state income taxes.

CECONY’s income tax expense increased to $218 million for the three months ended March 31, 2017 from $180 million for the three months ended March 31, 2016. CECONY's effective tax rate for the three months ended March 31, 2017 and 2016 was 39 percent and 37 percent, respectively. The increase in CECONY's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and research and development tax credits, offset in part by lower state income taxes.

Con Edison anticipates a federal consolidated net operating loss for 2017, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2017 net operating loss to recover $22 million of income tax and the remaining 2017 net operating loss, as well as general business tax credits generated in 2017, 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 March 31, 2017, the estimated liability for uncertain tax positions for Con Edison was $40 million ($21 million for CECONY). Con Edison reasonably expects to resolve approximately $33 million ($23 million, net of federal taxes) of its uncertain tax positions within the next twelve months, including $19 million ($13 million, net of federal taxes), which, if recognized, would reduce Con Edison’s effective tax rate. The amount related to CECONY is approximately $17 million ($12 million, net of federal taxes), including $2 million, which, 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 $23 million ($16 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, 2017, the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At March 31, 2017 and December 31, 2016, the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.