Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Supplemental Cash Flow Information [Line Items]
Interest and related charges, excluding capitalized amounts		$ 1,519	$ 1,643	$ 1,362
Income taxes		292	106	89
Significant noncash investing and financing activities:
Accrued capital expenditures	[1],[2],[3],[4],[5]	485	555	307
Leases	[1],[2],[3],[4],[5],[6]	173	157
Receivables from sales of assets and equity method investments	[1],[2],[3],[4],[5]		5	159
Virginia Electric and Power Company
Schedule Of Supplemental Cash Flow Information [Line Items]
Interest and related charges, excluding capitalized amounts		491	495	498
Income taxes		452	272	128
Significant noncash investing and financing activities:
Accrued capital expenditures	[5],[7]	262	292	$ 204
Leases	[5],[7],[8]	$ 32	$ 55

[1] See Note 3 for noncash investing and financing activities related to the SCANA Combination.

[2] See Note 5 for noncash activities related to the sale of a noncontrolling interest in Cove Point.

[3] See Note 9 for noncash investing activities related to the acquisition of a noncontrolling interest in Wrangler.

[4] See Notes 18,19 and 20 for noncash financing activities related to the acquisition of the public interest in Dominion Energy Midstream, the remarketing of RSNs, the issuance of stock purchase contracts associated with the 2019 Equity Units, the contribution of stock to Dominion Energy’s qualified defined benefit pension plan, derivative restructuring and the issuance of common stock associated with the settlement of litigation. See Note 23 for non-cash investing activities related to property, plant and equipment conveyed to satisfy litigation.

[5] See the New Accounting Standards section below for noncash investing and financing activities related to the adoption of a new accounting standard for leasing arrangements.

[6] Includes $46 million of finance leases and $127 million of operating leases at December 31, 2020 and $113 million of finance leases and $44 million of operating leases at December 31, 2019.

[7] See Note 18 for non-cash financing activities related to derivative restructuring.

[8] Includes $32 million of finance leases as of December 31, 2020 and $20 million of finance leases and $35 million of operating leases as of December 31, 2019.