Pension and Other Postretirement Benefits (OPEB) - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 19	$ 17	$ 37	$ 34
Defined benefit plan, expected future employer contributions, next fiscal year	100		100
Postretirement Healthcare Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	0	2	1	3
Defined benefit plan, expected future employer contributions, current fiscal year	5		5
Long Island Electric Utility Servco LLC Pension and OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected future employer contributions, current fiscal year	23		23
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	6	7	12	13
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Postretirement Healthcare Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total benefit costs	$ 4	$ 4	$ 7	$ 7