Derivatives and Hedge Accounting Activities (Volume of Derivative Activity) (Details) - 6 months ended Jun. 30, 2017 MMcf in Thousands		USD ($) MWh MMcf gal	EUR (€)
Fixed Price - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)	[1]	90
Fixed Price - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)	[1]	44
Fixed Price - Natural Gas - Current Derivative Contract | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		2
Fixed Price - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)	[1]	17
Fixed Price - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)	[1]	7
Basis - Natural Gas - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		158
Basis - Natural Gas - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		51
Basis - Natural Gas - Current Derivative Contract | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		2
Basis - Natural Gas - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		597
Basis - Natural Gas - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of derivative activity (bcf, Gal)		549
Fixed Price - Electricity - Current Derivative Contract
Derivative [Line Items]
Volume of electricity (MWh) | MWh		9,879,568
Fixed Price - Electricity - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity (MWh) | MWh	[1]	1,561,090
Fixed Price - Electricity - Non-current Derivative Contract
Derivative [Line Items]
Volume of electricity (MWh) | MWh		1,107,760
Fixed Price - Electricity - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity (MWh) | MWh	[1]	1,107,760
Financial Transmission Rights - Electricity- Current Derivative Contract
Derivative [Line Items]
Volume of electricity (MWh) | MWh		100,076,734
Financial Transmission Rights - Electricity- Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Volume of electricity (MWh) | MWh		95,128,929
Financial Transmission Rights - Electricity- Non-current Derivative Contract
Derivative [Line Items]
Volume of electricity (MWh) | MWh		0
Liquids - Current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal) | gal	[2]	53,831,712
Liquids - Current Derivative Contract | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Volume of derivative activity (bcf, Gal) | gal		45,767,712
Liquids - Non-current Derivative Contract
Derivative [Line Items]
Volume of derivative activity (bcf, Gal) | gal	[2]	0
Foreign currency
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | €	[3],[4]		€ 250,000,000
Foreign currency | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | €			€ 250,000,000
Foreign Exchange - Current Derivative Contract
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[3],[4]	$ 0
Foreign Exchange - Current Derivative Contract | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[5]	0
Foreign Exchange - Non- Current Derivative Contract
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[3],[4]	280,000,000
Foreign Exchange - Non- Current Derivative Contract | Dominion Energy Gas Holdings, LLC
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[5]	280,000,000
Interest Rate - Current Derivative Contract
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[4]	1,550,000,000
Interest Rate - Current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[6]	1,050,000,000
Interest Rate - Non-current Derivative Contract
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[4]	5,057,909,202
Interest Rate - Non-current Derivative Contract | Virginia Electric and Power Company
Derivative [Line Items]
Interest rate / Foreign currency (US Dollars, Euros) | $	[6]	$ 1,150,000,000

[1] Includes options.

[2] Includes NGLs and oil.

[3] Euro equivalent volumes are €250,000,000.

[4] Maturity is determined based on final settlement period.

[5] Maturity is determined based on final settlement period. Euro equivalent volumes are €250,000,000

[6] Maturity is determined based on final settlement period.