Regulatory Matters - Summary of Significant Virginia Power Electric Transmission Projects Applied (Detail) - Virginia Electric and Power Company $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) kV mi
Rebuild Clubhouse-Dry Bread Line and Dry Bread-Lakeview Line in Greensville County, Virginia
Public Utilities General Disclosures [Line Items]
Application Date	2020-11
Approval Date	July 2021
Type of Line | kV	230
Miles of Lines | mi	13
Cost Estimate | $	$ 25
Elmont-Ladysmith rebuild and related projects in the Counties of Hanover and Caroline, Virginia
Public Utilities General Disclosures [Line Items]
Application Date	2021-04
Approval Date	Pending
Type of Line | kV	500
Miles of Lines | mi	26
Cost Estimate | $	$ 95
Beaumeade-Belmont reconductor and rebuild projects in the County of Loudoun, Virginia
Public Utilities General Disclosures [Line Items]
Application Date	2021-05
Approval Date	Pending
Type of Line | kV	230
Miles of Lines | mi	7
Cost Estimate | $	$ 15
Extension to Cloud Switching Station and Easters Switching Station in the County of Mecklenburg, Virginia
Public Utilities General Disclosures [Line Items]
Application Date	2021-06
Approval Date	Pending
Type of Line | kV	230
Miles of Lines | mi	15
Cost Estimate | $	$ 105