Fair Value Measurements (Fair Value, Option, Quantitative Disclosures) (Details) $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($) $ / gal $ / MMBTU $ / MWh	Dec. 31, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 388	$ 719
Derivative liabilities		343	794
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		114
Derivative liabilities		19
Level 3 | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	[1]	97
Derivative liabilities	[1]	9
Level 3 | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		4
Derivative liabilities		7
Level 3 | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		9
Derivative liabilities		3
Level 3 | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	[2]	$ 4
Level 3 | Liabilities: | Minimum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	(2)
Level 3 | Liabilities: | Minimum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	2
Price Volatility	[4]	25.00%
Level 3 | Liabilities: | Minimum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3]	(9)
Level 3 | Liabilities: | Weighted Average | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3],[5]	2
Level 3 | Liabilities: | Weighted Average | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3],[5]	3
Price Volatility	[4],[5]	35.00%
Level 3 | Liabilities: | Weighted Average | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3],[5]	2
Level 3 | Liabilities: | Maximum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	3
Level 3 | Liabilities: | Maximum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	5
Price Volatility	[4]	58.00%
Level 3 | Liabilities: | Maximum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3]	9
Level 3 | Assets: | Minimum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	(2)
Credit Spread	[6]	1.00%
Level 3 | Assets: | Minimum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	2
Price Volatility	[4]	25.00%
Level 3 | Assets: | Minimum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3]	0
Level 3 | Assets: | Minimum | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[3]	(2)
Level 3 | Assets: | Weighted Average | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3],[5]	(1)
Credit Spread	[5],[6]	3.00%
Level 3 | Assets: | Weighted Average | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3],[5]	3
Price Volatility	[4],[5]	37.00%
Level 3 | Assets: | Weighted Average | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[3],[5]	1
Level 3 | Assets: | Weighted Average | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3],[5]	1
Level 3 | Assets: | Maximum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	8
Credit Spread	[6]	6.00%
Level 3 | Assets: | Maximum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[3]	3
Price Volatility	[4]	58.00%
Level 3 | Assets: | Maximum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[3]	2
Level 3 | Assets: | Maximum | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[3]	14
Dominion Gas Holdings, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 11	2
Derivative liabilities		14	9
Dominion Gas Holdings, LLC | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		6
Dominion Gas Holdings, LLC | Level 3 | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 6
Dominion Gas Holdings, LLC | Level 3 | Assets: | Minimum | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[7]	0
Dominion Gas Holdings, LLC | Level 3 | Assets: | Weighted Average | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[7],[8]	1
Dominion Gas Holdings, LLC | Level 3 | Assets: | Maximum | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / gal	[7]	1
Virginia Electric and Power Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 127	113
Derivative liabilities		86	$ 87
Virginia Electric and Power Company | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		101
Derivative liabilities		8
Virginia Electric and Power Company | Level 3 | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	[9]	92
Virginia Electric and Power Company | Level 3 | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		5
Virginia Electric and Power Company | Level 3 | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		9
Derivative liabilities		$ 3
Virginia Electric and Power Company | Level 3 | Liabilities: | Minimum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	(9)
Virginia Electric and Power Company | Level 3 | Liabilities: | Minimum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	2
Price Volatility	[11]	32.00%
Virginia Electric and Power Company | Level 3 | Liabilities: | Weighted Average | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10],[12]	3
Price Volatility	[11],[12]	35.00%
Virginia Electric and Power Company | Level 3 | Liabilities: | Weighted Average | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[10],[12]	2
Virginia Electric and Power Company | Level 3 | Liabilities: | Maximum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	9
Virginia Electric and Power Company | Level 3 | Liabilities: | Maximum | Gas | Physical and Financial Options:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	5
Price Volatility	[11]	38.00%
Virginia Electric and Power Company | Level 3 | Assets: | Minimum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	(2)
Credit Spread	[13]	1.00%
Virginia Electric and Power Company | Level 3 | Assets: | Minimum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[10]	(2)
Virginia Electric and Power Company | Level 3 | Assets: | Weighted Average | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10],[12]	(1)
Credit Spread	[12],[13]	3.00%
Virginia Electric and Power Company | Level 3 | Assets: | Weighted Average | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[10],[12]	1
Virginia Electric and Power Company | Level 3 | Assets: | Maximum | Gas | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MMBTU	[10]	4
Credit Spread	[13]	6.00%
Virginia Electric and Power Company | Level 3 | Assets: | Maximum | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market Price | $ / MWh	[10]	14

[1] Includes basis.

[2] Includes NGLs and oil.

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

[4] Represents volatilities unrepresented in published markets

[5] Averages weighted by volume.

[6] Represents credit spreads unrepresented in published markets.

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

[8] Averages weighted by volume.

[9] Includes basis.

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

[11] Represents volatilities unrepresented in published markets.

[12] Averages weighted by volume.

[13] Represents credit spreads unrepresented in published markets.