Schedule of Acquisitions of Solar Projects (Detail) $ in Millions		6 Months Ended
		Jun. 30, 2022 USD ($) MW	Jun. 30, 2021 USD ($)
Property Plant And Equipment [Line Items]
Project Cost		$ 121	$ 36
Acquisition of Solar Project Madison in Virginia
Property Plant And Equipment [Line Items]
Date Agreement Entered		2020-07
Date Agreement Closed		2020-07
Project Cost	[1]	$ 130
Date of Commercial Operations		Expected 2023
MW Capacity | MW		62
Acquisition of Solar Project Atlanta Farms in Ohio
Property Plant And Equipment [Line Items]
Date Agreement Entered		2022-03
Date Agreement Closed		May 2022
Project Cost	[1]	$ 390
Date of Commercial Operations	[2]	Expected split
MW Capacity | MW		200
Acquisition of Solar Project Hardin II in Ohio
Property Plant And Equipment [Line Items]
Date Agreement Entered		2020-08
Date Agreement Closed		Expected 2022
Project Cost	[1]	$ 295
Date of Commercial Operations		Expected 2023
MW Capacity | MW		150
Virginia Electric and Power Company
Property Plant And Equipment [Line Items]
Project Cost		$ 38	$ 19
Virginia Electric and Power Company | Acquisition of Solar Project Pumpkinseed in Virginia
Property Plant And Equipment [Line Items]
Date Agreement Entered		2020-05
Date Agreement Closed		2020-05
Project Cost	[3]	$ 140
Date of Commercial Operations		Expected 2022
MW Capacity | MW		60
Virginia Electric and Power Company | Acquisition of Solar Project Bookers Mill in Virginia
Property Plant And Equipment [Line Items]
Date Agreement Entered		2021-02
Date Agreement Closed		2021-06
Project Cost	[3]	$ 230
Date of Commercial Operations		Expected 2023
MW Capacity | MW		127

[1] Includes acquisition cost.

[2] Expected to be split between 2023 and 2024

[3] Includes acquisition cost