Fair Value Measurements (Fair Value Quantitative Disclosures) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2016 USD ($) $ / gal $ / MWh $ / MMBTU	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 279	$ 388
Derivative liabilities		155	343
Virginia Electric and Power Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		194	127
Derivative liabilities		31	86
Dominion Gas Holdings, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			11
Derivative liabilities		11	14
Level 3 | Virginia Electric and Power Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		152
Derivative liabilities		2
Level 3 | Dominion Gas Holdings, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		2
Fair Value, Measurements, Recurring | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		262	364
Derivative liabilities		96	160
Fair Value, Measurements, Recurring | Virginia Electric and Power Company | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		188	114
Derivative liabilities		10	27
Fair Value, Measurements, Recurring | Dominion Gas Holdings, LLC | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			11
Derivative liabilities		5
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		147
Derivative liabilities		8
Fair Value, Measurements, Recurring | Level 3 | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		147	114
Derivative liabilities		8	19
Fair Value, Measurements, Recurring | Level 3 | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	[1]	70
Derivative liabilities	[1]	2
Fair Value, Measurements, Recurring | Level 3 | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	[2]	3
Fair Value, Measurements, Recurring | Level 3 | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		7
Derivative liabilities		3
Fair Value, Measurements, Recurring | Level 3 | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		3
Fair Value, Measurements, Recurring | Level 3 | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 67
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Minimum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	(2)
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Minimum | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[3]	0
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Minimum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	(9)
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Maximum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	4
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Maximum | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[3]	2
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Maximum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	3
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Weighted Average | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3],[4]	4
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Weighted Average | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[3],[4]	1
Fair Value, Measurements, Recurring | Level 3 | Liabilities: | Weighted Average | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3],[4]	0
Fair Value, Measurements, Recurring | Level 3 | Assets: | Minimum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	(2)
Credit Spreads (percentage)	[5]	1.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Minimum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	(9)
Fair Value, Measurements, Recurring | Level 3 | Assets: | Minimum | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	2
Price Volatility (percentage)	[6]	18.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Minimum | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	21
Price Volatility (percentage)	[6]	14.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Maximum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	12
Credit Spreads (percentage)	[5]	4.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Maximum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	7
Fair Value, Measurements, Recurring | Level 3 | Assets: | Maximum | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3]	7
Price Volatility (percentage)	[6]	50.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Maximum | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3]	55
Price Volatility (percentage)	[6]	104.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Weighted Average | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3],[4]	0
Credit Spreads (percentage)	[4],[5]	2.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Weighted Average | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3],[4]	1
Fair Value, Measurements, Recurring | Level 3 | Assets: | Weighted Average | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[3],[4]	3
Price Volatility (percentage)	[4],[6]	24.00%
Fair Value, Measurements, Recurring | Level 3 | Assets: | Weighted Average | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[3],[4]	34
Price Volatility (percentage)	[4],[6]	31.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 145	101
Derivative liabilities		2	8
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	[7]	68
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		7
Derivative liabilities		2
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		3
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 67
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Liabilities: | Minimum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	(9)
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Liabilities: | Maximum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	3
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Liabilities: | Weighted Average | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8],[9]	0
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Minimum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8]	(2)
Credit Spreads (percentage)	[5]	1.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Minimum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	(9)
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Minimum | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8]	2
Price Volatility (percentage)	[10]	18.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Minimum | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	21
Price Volatility (percentage)	[10]	14.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Maximum | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8]	7
Credit Spreads (percentage)	[5]	4.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Maximum | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	7
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Maximum | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8]	7
Price Volatility (percentage)	[10]	34.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Maximum | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8]	55
Price Volatility (percentage)	[10]	104.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Weighted Average | Discounted Cash Flow | Commodity | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8],[9]	0
Credit Spreads (percentage)	[9],[11]	2.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Weighted Average | Discounted Cash Flow | Commodity | FTRs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8],[9]	1
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Weighted Average | Option Model | Physical and Financial Options: | Natural Gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MMBTU	[8],[9]	3
Price Volatility (percentage)	[9],[10]	24.00%
Fair Value, Measurements, Recurring | Level 3 | Virginia Electric and Power Company | Assets: | Weighted Average | Option Model | Electricity | Electricity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / MWh	[8],[9]	34
Price Volatility (percentage)	[9],[10]	31.00%
Fair Value, Measurements, Recurring | Level 3 | Dominion Gas Holdings, LLC | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets			$ 6
Derivative liabilities		$ 2
Fair Value, Measurements, Recurring | Level 3 | Dominion Gas Holdings, LLC | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		$ 2
Fair Value, Measurements, Recurring | Level 3 | Dominion Gas Holdings, LLC | Liabilities: | Minimum | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[12]	0
Fair Value, Measurements, Recurring | Level 3 | Dominion Gas Holdings, LLC | Liabilities: | Maximum | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[12]	2
Fair Value, Measurements, Recurring | Level 3 | Dominion Gas Holdings, LLC | Liabilities: | Weighted Average | Discounted Cash Flow | Commodity | NGL's
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price (per Dth, per Gal, per MWh) | $ / gal	[13]	1

[1] Includes basis.

[2] Includes NGLs and oil.

[3] Represents market prices beyond defined terms for Levels 1 and 2.

[4] Averages weighted by volume.

[5] Represents credit spreads unrepresented in published markets.

[6] Represents volatilities unrepresented in published markets.

[7] Includes basis.

[8] Represents market prices beyond defined terms for Levels 1 and 2.

[9] Averages weighted by volume.

[10] Represents volatilities unrepresented in published markets.

[11] Represents credit spreads unrepresented in published markets.

[12] Represents market prices beyond defined terms for Levels 1 and 2.

[13] Averages weighted by volume.