Fair Value Measurements (Fair Value, Option, Quantitative Disclosures) (Details) $ in Millions		9 Months Ended
		Sep. 30, 2015 USD ($) $ / MWh $ / MMBTU $ / gal	Dec. 31, 2014 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 406	$ 719
Fair Value of Derivative Liabilities		346	794
Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		137
Fair Value of Derivative Liabilities		14
Level 3 | Natural Gas | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[1]	99
Fair Value of Derivative Liabilities	[1]	10
Level 3 | Natural Gas | Physical and Financial Options:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		6
Fair Value of Derivative Liabilities		2
Level 3 | Liquids | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[2]	5
Level 3 | Electric | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		4
Level 3 | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		23
Fair Value of Derivative Liabilities		$ 2
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	(2)
Credit spread (percentage)	[4]	1.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	4
Credit spread (percentage)	[4]	6.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3],[5]	(1)
Credit spread (percentage)	[4],[5]	3.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	2
Price Volatility (percentage)	[6]	23.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	6
Price Volatility (percentage)	[6]	75.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3],[5]	4
Price Volatility (percentage)	[5],[6]	44.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Liquids | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[3]	0
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Liquids | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[3]	2
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Liquids | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[3],[5]	1
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	26
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	47
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3],[5]	45
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	(3)
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	12
Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3],[5]	2
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	(2)
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	4
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3],[5]	1
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	2
Price Volatility (percentage)	[6]	23.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3]	4
Price Volatility (percentage)	[6]	50.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[3],[5]	3
Price Volatility (percentage)	[5],[6]	34.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	(12)
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3]	12
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[3],[5]	1
Virginia Electric and Power Company
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 150	113
Fair Value of Derivative Liabilities		73	87
Virginia Electric and Power Company | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		122
Fair Value of Derivative Liabilities		2
Virginia Electric and Power Company | Level 3 | Natural Gas | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[7]	93
Virginia Electric and Power Company | Level 3 | Natural Gas | Physical and Financial Options:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		2
Virginia Electric and Power Company | Level 3 | Electric | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		4
Virginia Electric and Power Company | Level 3 | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		23
Fair Value of Derivative Liabilities		$ 2
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8]	(2)
Credit spread (percentage)	[9]	1.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8]	3
Credit spread (percentage)	[9]	6.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8],[10]	(1)
Credit spread (percentage)	[9],[10]	3.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8]	2
Price Volatility (percentage)	[11]	50.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8]	6
Price Volatility (percentage)	[11]	75.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Natural Gas | Physical and Financial Options: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MMBTU	[8],[10]	5
Price Volatility (percentage)	[10],[11]	66.00%
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	44
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	47
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | Electric | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8],[10]	45
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	(3)
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	12
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8],[10]	2
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	(12)
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | Natural Gas | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	12
Virginia Electric and Power Company | Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | FTRs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8],[10]	1
Dominion Gas Holdings, LLC
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 9	2
Fair Value of Derivative Liabilities		18	$ 9
Dominion Gas Holdings, LLC | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		4
Dominion Gas Holdings, LLC | Level 3 | NGLs | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 4
Dominion Gas Holdings, LLC | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | NGLs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[12]	0
Dominion Gas Holdings, LLC | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | NGLs | Physical and Financial Forwards and Futures: | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[12]	2
Dominion Gas Holdings, LLC | Level 3 | Fair Value, Option, Quantitative Disclosures, Assets | NGLs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[13]	1

[1] Includes basis.

[2] Includes NGLs and oil.

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

[4] Represents credit spreads unrepresented in published markets.

[5] Averages weighted by volume.

[6] Represents volatilities unrepresented in published markets.

[7] Includes basis.

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

[9] Represents credit spreads unrepresented in published markets.

[10] Averages weighted by volume.

[11] Represents volatilities unrepresented in published markets.

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

[13] Averages weighted by volume.