Fair Value Measurements (Fair Value, Option, Quantitative Disclosures) (Details) $ in Millions		6 Months Ended
		Jun. 30, 2015 USD ($) $ / MWh $ / MMBTU $ / gal	Dec. 31, 2014 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		$ 597	$ 719
Fair Value of Derivative Liabilities		453	794
Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		86
Fair Value of Derivative Liabilities		15
Level 3 | Natural Gas | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets	[1]	57
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		4
Fair Value of Derivative Liabilities		2
Level 3 | NGLs | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Liabilities	[2]	1
Level 3 | FTRs | Physical and Financial Forwards and Futures:
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		25
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]	5.00%
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]	22.00%
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]	4
Price Volatility (percentage)	[6]	69.00%
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]	3
Price Volatility (percentage)	[5],[6]	33.00%
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]	(2)
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]	10
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]	2
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]	22.00%
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]	69.00%
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]	33.00%
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | NGLs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[3]	1
Level 3 | Fair Value, Option, Quantitative Disclosures, Liabilities | NGLs | 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, Liabilities | NGLs | Physical and Financial Forwards and Futures: | Wieghted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / gal	[4],[5]	1
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]	(10)
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]	10
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		$ 117	113
Fair Value of Derivative Liabilities		21	$ 87
Virginia Electric and Power Company | Level 3
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Derivative Assets		75
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]	50
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		25
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]	5.00%
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 | FTRs | Physical and Financial Forwards and Futures: | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Market Price (per unit) | $ / MWh	[8]	(2)
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]	10
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) | $ / MMBTU	[8]	(10)
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) | $ / MMBTU	[8]	10
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

[1] Includes basis.

[2] Information represents Dominion Gas' quantitative information about Level 3 fair value measurement.

[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.