Employee Benefit Plans - EEGH - Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 1
Interest cost	5	6
Expected return on plan assets	(5)	(9)
Net amortization	(1)	(1)
Net periodic benefit cost (credit)	1	(3)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	3
Interest cost	20	23
Expected return on plan assets	(33)	(35)
Net amortization	6	9
Net periodic benefit cost (credit)	0	0
UNITED STATES | Pension Plan [Member] | Eastern Energy Gas Holdings, LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Interest cost	0	3
Expected return on plan assets	0	(14)
Net amortization	0	2
Net periodic benefit cost (credit)	0	(8)
UNITED STATES | Other Postretirement Benefits Plan [Member] | Eastern Energy Gas Holdings, LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Interest cost	0	1
Expected return on plan assets	0	(5)
Net amortization	0	(1)
Net periodic benefit cost (credit)	$ 0	$ (4)