Significant Accounting Policies (Reconciliation of Total Cash, Restricted Cash and Equivalents) (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019		Jun. 30, 2019	Dec. 31, 2018
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		$ 675	$ 166	[1]	$ 382	$ 268
Restricted cash and equivalents	[2]	67	103		178	123
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		742	269		560	391
Virginia Electric and Power Company
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents		37	17	[3]	17	29
Restricted cash and equivalents	[2]	3	7		8	9
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		40	24		25	38
Dominion Energy Gas Holdings, LLC
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	[4]	53	27	[5]	195	108
Restricted cash and equivalents	[2]	11	12		12	90
Cash, restricted cash and equivalents shown in the Consolidated Statements of Cash Flows		$ 64	$ 39		$ 207	$ 198

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Restricted cash and equivalent balances are presented within other current assets in the Companies’ Consolidated Balance Sheets.

[3] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[4] At June 30, 2019 and December 31, 2018, Dominion Energy Gas had $12 million and $9 million of cash and cash equivalents included in current assets of discontinued operations, respectively.

[5] Dominion Energy Gas’ Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.