Variable Interest Entities (VIEs) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Operating Revenues	$ 2,272	$ 1,903	$ 6,661	$ 6,666
Operation and Maintenance	765	807	2,310	2,368
Long Island ServCo [Member]
Variable Interest Entity [Line Items]
Operating Revenues	137	142	389	394
Operation and Maintenance	137	$ 142	389	$ 394
Ocean Wind JV Holdco
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	190		190		$ 111
Ocean Wind JV Holdco | Anticipated Spend
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 35		$ 35