Variable Interest Entities (VIEs) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Variable Interest Entity [Line Items]
Operating Revenues	$ 2,456	$ 2,272	$ 8,632	$ 6,661
Operation and Maintenance	792	765	2,279	2,310
Long Island ServCo [Member]
Variable Interest Entity [Line Items]
Operating Revenues	140	137	397	389
Operation and Maintenance	$ 140	$ 137	$ 397	$ 389