Variable Interest Entities (VIEs) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Operating Revenues	$ 11,237	$ 9,800	$ 9,722
Operation and Maintenance	3,150	3,178	3,226
Long Island ServCo [Member]
Variable Interest Entity [Line Items]
Operating Revenues	533	516	511
Operation and Maintenance	$ 533	$ 516	$ 511