Variable Interest Entities (VIEs) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Operating Revenues	$ 2,076	$ 1,874	$ 4,389	$ 4,763
Operation and Maintenance	751	783	1,545	1,561
Long Island ServCo [Member]
Variable Interest Entity [Line Items]
Operating Revenues	129	129	252	252
Operation and Maintenance	129	$ 129	252	$ 252
Ocean Wind JV Holdco
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	165		165		$ 111
Ocean Wind JV Holdco | Anticipated Spend
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 100		$ 100