Goodwill	12 Months Ended
Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill In 2018 and 2017, Con Edison elected to perform the optional qualitative assessment for goodwill related to the 1999 O&R merger and the gas storage company, and the first step of the quantitative test for the residential solar company. In 2018 and 2017, Con Edison completed impairment tests for its goodwill of $406 million related to the O&R merger, and determined that it was not impaired. For the impairment test, $245 million and $161 million of goodwill were allocated to CECONY and O&R, respectively. In 2018 and 2017, Con Edison completed impairment tests for goodwill of $8 million related to a gas storage company acquired by CET Gas from Con Edison Development and determined that it was not impaired. In 2016, Con Edison completed impairment tests for goodwill of $15 million related to two energy services companies owned by the Clean Energy Businesses and determined that goodwill was impaired and, upon calculating the implied fair value of goodwill using fair values based primarily on discounted cash flows, recorded a corresponding impairment charge of $15 million ($12 million, net of tax). In 2018 and 2017, Con Edison determined that goodwill of $14 million related to the residential solar company acquired by the Clean Energy Businesses in 2016 was not impaired. In 2018 the Clean Energy Businesses acquired a battery storage company and recorded $12 million of goodwill as part of the purchase price allocation. Estimates of future cash flows, projected growth rates, and discount rates inherent in the cash flow estimates for Con Edison subsidiaries other than the Utilities may vary significantly from actual results, which could result in a future impairment of goodwill.

Goodwill

In 2018 and 2017, Con Edison elected to perform the optional qualitative assessment for goodwill related to the 1999 O&R merger and the gas storage company, and the first step of the quantitative test for the residential solar company. In 2018 and 2017, Con Edison completed impairment tests for its goodwill of $406 million related to the O&R merger, and determined that it was not impaired. For the impairment test, $245 million and $161 million of goodwill were allocated to CECONY and O&R, respectively. In 2018 and 2017, Con Edison completed impairment tests for goodwill of $8 million related to a gas storage company acquired by CET Gas from Con Edison Development and determined that it was not impaired. In 2016, Con Edison completed impairment tests for goodwill of $15 million related to two energy services companies owned by the Clean Energy Businesses and determined that goodwill was impaired and, upon calculating the implied fair value of goodwill using fair values based primarily on discounted cash flows, recorded a corresponding impairment charge of $15 million ($12 million, net of tax). In 2018 and 2017, Con Edison determined that goodwill of $14 million related to the residential solar company acquired by the Clean Energy Businesses in 2016 was not impaired. In 2018 the Clean Energy Businesses acquired a battery storage company and recorded $12 million of goodwill as part of the purchase price allocation. Estimates of future cash flows, projected growth rates, and discount rates inherent in the cash flow estimates for Con Edison subsidiaries other than the Utilities may vary significantly from actual results, which could result in a future impairment of goodwill.