Pension, OPEB and Savings Plans (Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2021 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	$ 402
Payments Expected Year Two	386
Payments Expected Year Three	397
Payments Expected Year Four	405
Payments Expected Year Five	414
Payments Expected Thereafter	2,154
Total Estimated Future Benefit Payments	4,158
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	82
Payments Expected Year Two	82
Payments Expected Year Three	82
Payments Expected Year Four	81
Payments Expected Year Five	80
Payments Expected Thereafter	368
Total Estimated Future Benefit Payments	775
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	10
Payments Expected Year Two	12
Payments Expected Year Three	14
Payments Expected Year Four	17
Payments Expected Year Five	19
Payments Expected Thereafter	136
Total Estimated Future Benefit Payments	208
Long Island Electric Utility Servco LLC Pension and OPEB [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Payments Expected Next Twelve Months	9
Payments Expected Year Two	11
Payments Expected Year Three	13
Payments Expected Year Four	14
Payments Expected Year Five	16
Payments Expected Thereafter	104
Total Estimated Future Benefit Payments	$ 167