Related-Party Transactions (Virginia Power) (Narrative) (Details) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Derivative Asset		$ 249,000,000	[1]		$ 249,000,000	[1]		$ 279,000,000	[2]
Derivative Liabilities		118,000,000	[3]		118,000,000	[3]		155,000,000	[4]
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Derivative Asset	[2]	168,000,000			168,000,000			194,000,000
Derivative Liabilities	[4]	61,000,000			61,000,000			31,000,000
Short term demand note		36,000,000			36,000,000			262,000,000	[5]
Outstanding borrowings, net of repayments, under money pool for non-regulated subsidiaries		$ 0			$ 0			0
Issuance of common stock (in shares)		0		0	0		0
Virginia Electric and Power Company | Pension Benefits | Amounts Associated with the Dominion Pension Plan
Related Party Transaction [Line Items]
Amounts due to Dominion		$ 478,000,000			$ 478,000,000			396,000,000
Virginia Electric and Power Company | Dominion Retiree Health and Welfare plan | Amounts Associated with the Dominion Retiree Health and Welfare Plan
Related Party Transaction [Line Items]
Amounts due to Dominion		182,000,000			182,000,000			130,000,000
Virginia Electric and Power Company | Affiliate
Related Party Transaction [Line Items]
Derivative Asset		13,000,000			13,000,000			41,000,000
Derivative Liabilities		5,000,000			5,000,000			8,000,000
Virginia Electric and Power Company | Principal Owner
Related Party Transaction [Line Items]
Short term demand note		$ 36,000,000			$ 36,000,000			$ 262,000,000

[1] Noncurrent derivative assets are presented in other deferred charges and other assets in Dominion Energy’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred charges and other assets in Virginia Power's Consolidated Balance Sheets.

[3] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Dominion Energy’s Consolidated Balance Sheets.

[4] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Virginia Power’s Consolidated Balance Sheets.

[5] Virginia Power’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.