Goodwill	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill In 2019 and 2018, Con Edison elected to perform the optional qualitative assessment for goodwill related to the 1999 O&R merger and the acquisition of a gas storage company, and the first step of the quantitative test for the acquisition of a residential solar company. In 2019 and 2018, 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 2019 and 2018, Con Edison completed impairment tests for goodwill of $8 million related to a gas storage company acquired by CET Gas from the Clean Energy Businesses and determined that it was not impaired. In 2019 and 2018, 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, Con Edison recorded $12 million of goodwill related to a battery storage company acquired by the Clean Energy Businesses, and, in 2019, the amount was increased to $18 million, reflecting final purchase price adjustments. In 2019, Con Edison elected to perform the first step of the quantitative test for goodwill related to the battery storage company acquisition and determined that it was not impaired. 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.