Acquisitions, Investments and Dispositions - Con Edison Solutions' Retail Electric Supply Business (Details) - Con Edison Solutions - Retail Electric Supply Business - Discontinued Operations, Disposed of by Sale $ in Millions	1 Months Ended
	Sep. 30, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business	$ 235
Gain on sale of business	104
Gain on sale of business, after tax	56
Gain on sale of derivatives	65
Gain on sale of derivatives, after tax	42
Tax effect of sale, state tax related to change in apportionment of state income taxes	16
Tax effect of sale, state tax related to change in apportionment of state income taxes, net of federal tax	$ 10