Pension, OPEB and Savings Plans (Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	$ 364
Payments Expected Year Two	325
Payments Expected Year Three	331
Payments Expected Year Four	338
Payments Expected Year Five	343
Payments Expected Thereafter	1,758
Total Estimated Future Benefit Payments	3,459
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	74
Payments Expected Year Two	73
Payments Expected Year Three	71
Payments Expected Year Four	69
Payments Expected Year Five	67
Payments Expected Thereafter	288
Total Estimated Future Benefit Payments	642
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	15
Payments Expected Year Two	17
Payments Expected Year Three	20
Payments Expected Year Four	23
Payments Expected Year Five	25
Payments Expected Thereafter	167
Total Estimated Future Benefit Payments	267
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	12
Payments Expected Year Two	14
Payments Expected Year Three	16
Payments Expected Year Four	18
Payments Expected Year Five	20
Payments Expected Thereafter	125
Total Estimated Future Benefit Payments	$ 205