Risk Management and Hedging Activities - EEGH - Narrative (Details) - customer	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
EGTS
Derivative [Line Items]
Number of customers serviced	278
Revenue | Customer concentration risk | EEGH | Export customers
Derivative [Line Items]
Concentration risk, percentage	40.00%	34.00%
Revenue | Customer concentration risk | EEGH | Eastern Energy's largest customer
Derivative [Line Items]
Concentration risk, percentage	20.00%	17.00%
Revenue, product and service | Customer concentration risk | EGTS | Storage and transportation | Directly to consumer
Derivative [Line Items]
Concentration risk, percentage	98.00%
Revenue, product and service | Customer concentration risk | EGTS | Ten largest customers | Storage and transportation
Derivative [Line Items]
Concentration risk, percentage	38.00%
Revenue, product and service | Customer concentration risk | EGTS | Thirty largest customers | Storage and transportation
Derivative [Line Items]
Concentration risk, percentage	71.00%