Derivatives and Hedge Accounting Activities (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions		Sep. 30, 2017		Dec. 31, 2016
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		$ 246		$ 272
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		246		272
Total derivatives, not subject to a master netting or similar arrangement		3		7
Gross Amounts of Recognized Assets, Total		249		279
Derivative Asset		249	[1]	279	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		39		67
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		207		205
Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		156		153
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		156		153
Total derivatives, not subject to a master netting or similar arrangement		12		41
Gross Amounts of Recognized Assets, Total		168		194
Derivative Asset	[2]	168		194
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		1		2
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		155		151
Dominion Energy Gas Holdings, LLC
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		26		0
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		26		0
Gross Amounts of Recognized Assets, Total		26		0
Derivative Asset		26
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		4
Net Amounts		22
Commodity | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		186		211
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		186		211
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		8		14
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		178		197
Commodity | Over-the-counter | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		156		147
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		156		147
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		1		2
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		155		145
Commodity | Over-the-counter | Dominion Energy Gas Holdings, LLC
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		1		0
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		1		0
Net Amounts		1
Commodity | Exchange
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		24		44
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		24		44
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		21		44
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		3		0
Interest rate | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		11		17
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		11		17
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		6		9
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		5		8
Interest rate | Over-the-counter | Virginia Electric and Power Company
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		0		6
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		0		6
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		0		0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		0		6
Foreign currency | Over-the-counter
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		25		0
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		25		0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		4		0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received		0		0
Net Amounts		21		0
Foreign currency | Over-the-counter | Dominion Energy Gas Holdings, LLC
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets		25		0
Gross Amounts Offset in the Consolidated Balance Sheet		0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheet		25		$ 0
Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments		4
Net Amounts		$ 21

[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.