Employee Benefit Plans - EEGH - Pension Remeasurement (Details) - Eastern Energy Gas Holdings, LLC [Member] - Pension Benefit Plan Associated With GT&S Transaction [Member] $ in Millions	3 Months Ended
	Sep. 30, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Increase (Decrease) For Remeasurement Due To Curtailment	$ 7
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease For Remeasurement Due To Curtailment	$ 3
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.16%